Added tools/linter along with jest tests.

[nhtruong]

Description

Added a Linter to validate all yaml files in the /spec folder

Issues Resolved

#205
(Not closing as we still need to turn this into a workflow with a follow-up PR)

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[github-actions]

API specs implemented for 246/649 (37%) APIs.

[dblock]

Looks good.

1. Add the linter build/test to CI part of this commit (even if you want to add linting itself as part of another), so future changes to the linter are tested.
2. How much of the linter is OpenSearch-specific? Longer term, I wonder if it should be built as its own project in its own repo.

[nhtruong]

@dblock
2. How much of the linter is OpenSearch-specific? Longer term, I wonder if it should be built as its own project in its own repo.

Half of the validator rules are OpenSearch specific:

• Rules regarding x-operation-group
• Rules regarding parameter naming conventions

The other rules enforce the multi-file structure we created for OpenSearch (divinding paths into namespaces in schemas into categories). The merger tool assumes that there are no infractions in these rules to ensure that the result single-file is a valid OpenAPI file. Projects that want to reuse this structure will benefit from these (Though the namespace is actually a part of x-operation-group so we will have to untangle that first.)

[github-actions]

API specs implemented for 246/649 (37%) APIs.

[github-actions]

API specs implemented for 246/649 (37%) APIs.