feat: add Redis cluster mode support (Alpha)

[erhhung]

This PR is a revival or PR #14001 that has gone stale due to lack of follow-up by the original PR contributor @mie00. I have applied the original PR changes, rebased against the master branch, and changed the new CLI parameter and environment variable names to be consistent with existing names.

To re-iterate, this PR adds support for Redis running in cluster mode by:

• referencing instantiated Redis client using the redis.UniversalClient interface abstraction
• introducing new --redis-cluster-mode CLI parameter and REDIS_CLUSTER_MODE environment variable (true/false) to use redis.ClusterClient instead of redis.Client
• updating base manifests to set REDIS_CLUSTER_MODE environment variable using the redis.cluster.mode value in the argocd-cmd-params-cm ConfigMap

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the Title of the PR
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Does this PR require documentation updates?
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My build is green (troubleshooting builds).
• My new feature complies with the feature status guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.
• Optional. My organization is added to USERS.md.
• Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

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[codecov]

Codecov Report

❌ Patch coverage is 33.89831% with 39 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.18%. Comparing base (e80395b) to head (599a1f7).
⚠️ Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
util/cache/cache.go	26.00%	34 Missing and 3 partials ⚠️
cmd/argocd-server/commands/argocd_server.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #25115      +/-   ##
==========================================
- Coverage   62.29%   62.18%   -0.11%     
==========================================
  Files         351      351              
  Lines       49213    49253      +40     
==========================================
- Hits        30656    30629      -27     
- Misses      15640    15687      +47     
- Partials     2917     2937      +20     

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[erhhung]

Sorry about all the duplicate rebase commits—didn't want to risk any issues by dropping any from history, so please perform a squash merge if the PR is acceptable.

[todaywasawesome]

Can you sign all your commits? I also think you might need to bring a cleaner commit history here, it makes these more difficult to review an introduces risk.

I suggest starting with a new branch and applying your changes there first so you can bring in a clean history.