Manual backport of Improvement- Added helm inputs for managing audit logs into release/1.2.x

[Ganeshrockz]

Backport

This PR is manually created from #2265 to be assessed for backporting targeting the release/1.2.x.

The below text is copied from the body of the original PR.

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Changes proposed in this PR:

• Adds the relevant inputs in values.yaml to configure audit logging in Consul enterprise.
• Behind the scenes, values get translated to the json configuration present here and the whole configuration is added as a file in the Consul server's config map.

How I've tested this PR:

• Unit tests
• CI

How I expect reviewers to test this PR:

• I've added the auditLog field under server. Should the same be added to client?

Checklist:

• Tests added
• CHANGELOG entry added

  HashiCorp engineers only, community PRs should not add a changelog entry.
  Entries should use present tense (e.g. Add support for...)

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[david-yu]

@Ganeshrockz We should merge this PR into 1.2.x after GA since code freeze happened yesterday.

[david-yu]

Looks safe to merge now that tests are passing.