Deprecate ArtifactVersion.kind

[t-kikuc]

What this PR does:

• removed sdk.ArtifactVersion.Kind
• deprecate model.ArtifactVersion.kind (not deleted)

After merging this PR, we need to update the official plugins.

Let's delete model.ArtifactVersion.kind later. For now, we need it for backward compatibility.

Why we need it:

• to clean unused kind from the SDK

Which issue(s) this PR fixes:

Fixes https://github.com/pipe-cd/piped-plugin-sdk-go/issues/3

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 28.46%. Comparing base (d73300d) to head (e76df38).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5939      +/-   ##
==========================================
- Coverage   28.47%   28.46%   -0.01%     
==========================================
  Files         520      520              
  Lines       56415    56402      -13     
==========================================
- Hits        16063    16056       -7     
+ Misses      39086    39080       -6     
  Partials     1266     1266              

Flag	Coverage Δ
.	23.76% <ø> (+0.01%)	⬆️
.-pkg-app-pipedv1-plugin-example	0.00% <ø> (ø)
.-pkg-app-pipedv1-plugin-kubernetes	66.42% <ø> (ø)
.-pkg-app-pipedv1-plugin-kubernetes_multicluster	67.51% <ø> (ø)
.-pkg-app-pipedv1-plugin-wait	35.51% <ø> (ø)
.-pkg-plugin-sdk	48.86% <ø> (-0.37%)	⬇️
.-tool-actions-gh-release	19.23% <ø> (ø)
.-tool-actions-plan-preview	25.30% <ø> (ø)
.-tool-codegen-protoc-gen-auth	0.00% <ø> (ø)

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[Warashi]

LGTM

[khanhtc1202]

LGTM 👌