Explain all and Get all API

[bowenlan-amzn]

Issue #, if available:
#292

Description of changes:
Explain and Get Policy API now support get all functionality, to use it, just don't give any specific query object, directly call GET _opendistro/_ism/explain or _opendistro/_ism/policies, then you can retrieve all managed indices or all policies.

Such get all API can have several query parameters, for example:
GET _opendistro/_ism/policies?from=0&size=20&sortOrder=desc&sortField=policy.last_updated_time&queryString=p*

Transport action name of get all policies API is cluster:admin/opendistro/ism/policy/search
to be consistent with ODFE permission names

Testing

The IT for Get all policies and Explain All are in IndexStateManagementRestApiIT.kt and RestExplainActionIT.kt

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

---

Example req and res

GET _opendistro/_ism/policies

{
  "policies" : [
    {
      "_id" : "test",
      "_seq_no" : 0,
      "_primary_term" : 1,
      "policy" : {
        "policy_id" : "test",
        "description" : "A simple default policy that changes the replica count between hot and cold states.",
        "last_updated_time" : 1611712067239,
        "schema_version" : 1,
        "error_notification" : null,
        "default_state" : "hot",
        "states" : [
          {
            "name" : "hot",
            "actions" : [
              {
                "replica_count" : {
                  "number_of_replicas" : 0
                }
              }
            ],
            "transitions" : [ ]
          }
        ]
      }
    }
  ],
  "total_policies" : 1
}

GET _opendistro/_ism/explain

{
  "testindex1" : {
    "index.opendistro.index_state_management.policy_id" : "test",
    "index" : "testindex1",
    "index_uuid" : "WfnICHPuQ9OlYLXupg96Uw",
    "policy_id" : "test",
    "enabled" : true
  },
  "wildindex" : {
    "index.opendistro.index_state_management.policy_id" : "test",
    "index" : "wildindex",
    "index_uuid" : "47zfTb3JSfe9PGP287glMQ",
    "policy_id" : "test",
    "policy_seq_no" : 0,
    "policy_primary_term" : 1,
    "state" : {
      "name" : "hot",
      "start_time" : 1611712523140
    },
    "retry_info" : {
      "failed" : false,
      "consumed_retries" : 0
    },
    "info" : {
      "message" : "Successfully initialized policy: test"
    },
    "enabled" : true
  },
  "total_managed_indices" : 2
}

GET _opendistro/_ism/explain/testindex1,wildindex

{
  "testindex1" : {
    "index.opendistro.index_state_management.policy_id" : "test",
    "index" : "testindex1",
    "index_uuid" : "WfnICHPuQ9OlYLXupg96Uw",
    "policy_id" : "test",
    "policy_seq_no" : 0,
    "policy_primary_term" : 1,
    "policy_completed" : true
  },
  "wildindex" : {
    "index.opendistro.index_state_management.policy_id" : "test",
    "index" : "wildindex",
    "index_uuid" : "47zfTb3JSfe9PGP287glMQ",
    "policy_id" : "test",
    "policy_seq_no" : 0,
    "policy_primary_term" : 1,
    "policy_completed" : true
  }
}

GET _opendistro/_ism/explain/test*

{
  "testindex1" : {
    "index.opendistro.index_state_management.policy_id" : "test",
    "index" : "testindex1",
    "index_uuid" : "WfnICHPuQ9OlYLXupg96Uw",
    "policy_id" : "test",
    "policy_seq_no" : 0,
    "policy_primary_term" : 1,
    "policy_completed" : true
  }
}

GET _opendistro/_ism/explain?queryString=test*
total managed indices is determined by search response, according to previous logic

{
  "testindex1" : {
    "index.opendistro.index_state_management.policy_id" : "test",
    "index" : "testindex1",
    "index_uuid" : "WfnICHPuQ9OlYLXupg96Uw",
    "policy_id" : "test",
    "policy_seq_no" : 0,
    "policy_primary_term" : 1,
    "state" : {
      "name" : "hot",
      "start_time" : 1611712582258
    },
    "retry_info" : {
      "failed" : false,
      "consumed_retries" : 0
    },
    "info" : {
      "message" : "Successfully initialized policy: test"
    },
    "enabled" : true
  },
  "total_managed_indices" : 1
}

[codecov]

Codecov Report

Merging #352 (1c36ca3) into master (7e52f26) will increase coverage by 0.40%.
The diff coverage is 91.26%.

@@             Coverage Diff              @@
##             master     #352      +/-   ##
============================================
+ Coverage     76.72%   77.13%   +0.40%     
- Complexity     1460     1487      +27     
============================================
  Files           188      194       +6     
  Lines          7335     7552     +217     
  Branches       1190     1210      +20     
============================================
+ Hits           5628     5825     +197     
- Misses         1061     1071      +10     
- Partials        646      656      +10     

Impacted Files	Coverage Δ	Complexity Δ
...ndexstatemanagement/IndexStateManagementHistory.kt	76.19% <ø> (ø)	26.00 <0.00> (ø)
...agement/indexstatemanagement/ManagedIndexRunner.kt	55.04% <ø> (ø)	41.00 <0.00> (ø)
...indexstatemanagement/model/ManagedIndexMetaData.kt	90.06% <ø> (+0.62%)	41.00 <0.00> (ø)
.../indexstatemanagement/model/action/ActionConfig.kt	84.61% <ø> (ø)	9.00 <0.00> (ø)
...ement/step/forcemerge/AttemptCallForceMergeStep.kt	66.66% <ø> (ø)	7.00 <0.00> (ø)
...action/changepolicy/TransportChangePolicyAction.kt	76.72% <ø> (ø)	4.00 <0.00> (ø)
...gement/transport/action/explain/ExplainResponse.kt	100.00% <ø> (ø)	8.00 <0.00> (ø)
...ment/indexstatemanagement/util/RestHandlerUtils.kt	100.00% <ø> (ø)	0.00 <0.00> (ø)
...nt/refreshanalyzer/RefreshSearchAnalyzerRequest.kt	50.00% <ø> (ø)	1.00 <0.00> (ø)
...nt/transport/action/getpolicy/GetPoliciesAction.kt	66.66% <66.66%> (ø)	2.00 <2.00> (?)
... and 24 more

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[dbbaughe]

Can you add example request/responses to the PR description? Want to see what they look like; try adding different examples, e.g. of no indices (all), multiple indices, wildcards etc.