Add base plugin code for k8s multicluster plugin

[ffjlabo]

What this PR does:

as title.
I copied almost all from the example plugin.

Why we need it:

We decided to implement multi-cluster features as another plugin.

Which issue(s) this PR fixes:

Part of #5006

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

Attention: Patch coverage is 0% with 16 lines in your changes missing coverage. Please review.

Project coverage is 26.26%. Comparing base (7d9c00c) to head (8b1e3af).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...p/pipedv1/plugin/kubernetes_multicluster/plugin.go	0.00%	10 Missing ⚠️
...app/pipedv1/plugin/kubernetes_multicluster/main.go	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5592      +/-   ##
==========================================
- Coverage   26.27%   26.26%   -0.01%     
==========================================
  Files         470      472       +2     
  Lines       50372    50388      +16     
==========================================
  Hits        13234    13234              
- Misses      36078    36094      +16     
  Partials     1060     1060              

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[khanhtc1202]

👍

[t-kikuc]

lgtm

[t-kikuc]

Maybe we will use RegisterDeploymentPlugin(...) after starting implementing the DeploymentPlugin