Introduce piped plugins approvers group to CODEOWNER

[khanhtc1202]

What this PR does:

Introduce piped plugin approvers group and add it to CODEOWNER.
Welcome @mohammedfirdouss and @armistcxy as first plugins approvers in that group. Thanks a lot for your contributions 🚀

Why we need it:

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 29.32%. Comparing base (662ddc3) to head (f74576f).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6876   +/-   ##
=======================================
  Coverage   29.32%   29.32%           
=======================================
  Files         601      601           
  Lines       64213    64213           
=======================================
  Hits        18831    18831           
  Misses      43915    43915           
  Partials     1467     1467           

Flag	Coverage Δ
.	23.14% <ø> (ø)
.-pkg-app-pipedv1-plugin-analysis	32.43% <ø> (ø)
.-pkg-app-pipedv1-plugin-ecs	31.74% <ø> (ø)
.-pkg-app-pipedv1-plugin-kubernetes	58.37% <ø> (ø)
.-pkg-app-pipedv1-plugin-kubernetes_multicluster	59.39% <ø> (ø)
.-pkg-app-pipedv1-plugin-scriptrun	54.83% <ø> (ø)
.-pkg-app-pipedv1-plugin-terraform	37.95% <ø> (ø)
.-pkg-app-pipedv1-plugin-wait	33.04% <ø> (ø)
.-pkg-app-pipedv1-plugin-waitapproval	52.71% <ø> (ø)
.-pkg-plugin-sdk	50.34% <ø> (ø)
.-tool-actions-gh-release	19.23% <ø> (ø)
.-tool-actions-plan-preview	25.51% <ø> (ø)
.-tool-codegen-protoc-gen-auth	0.00% <ø> (ø)

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