Add support for TOML secret_store section

Viceroy is being updated with a new `local_server.secret_store` configuration section. Viceroy change:
fastly/Viceroy#210

This change adds support for the new Secret Store configuration section.

Related change:
#717

Author: awilliams-fastly

pkg/manifest/manifest.go

@@ -252,6 +252,7 @@ type LocalServer struct {
 	Backends     map[string]LocalBackend       `toml:"backends"`
 	Dictionaries map[string]LocalDictionary    `toml:"dictionaries,omitempty"`
 	ObjectStore  map[string][]LocalObjectStore `toml:"object_store,omitempty"`
+	SecretStore  map[string][]LocalSecretStore `toml:"secret_store,omitempty"`
 }
 
 // LocalBackend represents a backend to be mocked by the local testing server.
@@ -276,6 +277,13 @@ type LocalObjectStore struct {
 	Data string `toml:"data,omitempty"`
 }
 
+// LocalSecretStore represents a secret_store to be mocked by the local testing server.
+type LocalSecretStore struct {
+	Key  string `toml:"key"`
+	Path string `toml:"path,omitempty"`
+	Data string `toml:"data,omitempty"`
+}
+
 // Exists yields whether the manifest exists.
 //
 // Specifically, it indicates that a toml.Unmarshal() of the toml disk content

pkg/manifest/testdata/fastly-viceroy-update.toml

@@ -45,3 +45,14 @@ qux"""
     [[local_server.object_store.store_two]]
       key = "second"
       path = "strings.json"
+
+  [local_server.secret_store]
+    store_one = [{key = "first", data = "This is some secret data"}, {key = "second", path = "/path/to/secret.json"}]
+
+    [[local_server.secret_store.store_two]]
+      key = "first"
+      data = "This is also some secret data"
+
+    [[local_server.secret_store.store_two]]
+      key = "second"
+      path = "/path/to/other/secret.json"