fix: improve error messages

[sudo-suhas]

• Include plugin name in the error message when it is not found.
• Include the validation failure message along with the line number in
  the error message for plugin config.
• During lint, include the recipe name while printing errors that are
  neither 'not found' nor 'invalid config' errors.
• During run, on run failure, include recipe name in the error log
  context.
• Include details of the validation failures in the error message for
  InvalidConfigError. This gets printed while trying to run the recipe.

BEFORE:

$ meteor run run ./_recipes/caramlstore-stg-wth-script-invalid.yaml
INFO[0000] running recipe                                recipe=caramlstore-stg-wth-script-invalid
ERRO[0000] error running recipe                          duration_ms=189 err="failed to setup processor: could not initiate processor \"script\": script processor init: invalid  config" recipe=caramlstore-stg-wth-script-invalid records_count=0
ERRO[0000] failed to setup processor: could not initiate processor "script": script processor init: invalid  config
...

$ meteor lint ./_recipes
caramlstore-stg-wth-script-invalid: invalid script processor config on line: 13
caramlstore-stg-wth-script-invalid: invalid script processor config: Key: 'Config.script' Error:Field validation for 'script' failed on the 'required' tag
recipe error: urn scope is required to generate unique urn
kafka-to-http: invalid labels processor config: Key: 'Config.labels' Error:Field validation for 'labels' failed on the 'required' tag
service_yaml-test: invalid extractor on line: 4
shield-integration: invalid shield extractor config: Key: 'Config.host' Error:Field validation for 'host' failed on the 'required' tag
...

AFTER:

$ meteor run run ./_recipes/caramlstore-stg-wth-script-invalid.yaml
INFO[0000] running recipe                                recipe=caramlstore-stg-wth-script-invalid
ERRO[0000] error running recipe                          duration_ms=205 err="failed to setup processor: could not initiate processor \"script\": script processor init: invalid config:     * validation for field 'engine' failed on the 'oneof' tag\n\t * validation for field 'script' failed on the 'required' tag" recipe=caramlstore-stg-wth-script-invalid records_count=0
ERRO[0000] failed to setup processor: could not initiate processor "script": script processor init: invalid config:
     * validation for field 'engine' failed on the 'oneof' tag
     * validation for field 'script' failed on the 'required' tag  recipe=caramlstore-stg-wth-script-invalid
...

$ meteor lint ./_recipes
caramlstore-stg-wth-script-invalid: invalid script processor config on line: 13: validation for field 'engine' failed on the 'oneof' tag
caramlstore-stg-wth-script-invalid: invalid script processor config: validation for field 'script' failed on the 'required' tag
kafka-to-http: recipe error: urn scope is required to generate unique urn
kafka-to-http: invalid labels processor config: validation for field 'labels' failed on the 'required' tag
service_yaml-test: invalid 'service_yaml' extractor on line: 4
shield-integration: invalid shield extractor config: validation for field 'host' failed on the 'required' tag

Closes #416

[ravisuhag]

@sudo-suhas can you also add test cases for maintaining code coverage? The pipeline will break without that.

[sudo-suhas]

Have added tests where possible but haven't added any tests for the logging changes. W.r.t coverage, we aren't measuring the coverage for tests that have the //go:build plugins tag. Also, the way we calculate the difference in coverage is incorrect(check https://coveralls.io/builds/54400061 for example). See #429.