Backport of Improve ux to help users avoid overwriting fields of ACL tokens, roles and policies into release/1.15.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #16288 to be assessed for backporting due to the inclusion of the label backport/1.15.

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

---

Description

• Marking mergePolicies for deprecation and encouraging the use of -append-policy-id and -append-policy-name to reduce the ambiguity when overwriting fields on update
• Updating docs to clarify that using: -policy-id and -policy-name will overwrite existing policies
• Marking mergeRoles for deprecation and encouraging the use of -append-role-id and -append-role-name to reduce the ambiguity when overwriting fields on update
• Updating docs to clarify that using: -append-role-id and -append-role-name will overwrite existing policies

TODO

• add tests cases
• update description
• Do exact thing for -merge-roles as we did for -merge-policies
• add change-log
• de-duplicate all the logics

Testing & Reproduction steps

• In the case of bugs, describe how to replicate
• If any manual tests were done, document the steps and the conditions to replicate
• Call out any important/ relevant unit tests, e2e tests or integration tests you have added or are adding

Links

• current docs

PR Checklist

• updated test coverage
• external facing docs updated
• not a security concern

---

Overview of commits

• 5a10c73 - dbf3a19 - 29a84c4 - 63d2fb4 - f404886 - e7c0a45 - 5a37d37

[github-team-consul-core-pr-approver]

Auto approved Consul Bot automated PR