Use new plugin sdk interface to build example plugin

[Warashi]

What this PR does:

as title

Why we need it:

Because we introduced a new plugin SDK interface in #5698, I want to migrate the example.
After migrating all plugins, I'll remove and refactor old SDK interfaces.

Which issue(s) this PR fixes:

Follows #5698
Part of #5530

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 5 lines in your changes missing coverage. Please review.

Project coverage is 25.66%. Comparing base (21db8a8) to head (60f0cac).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/app/pipedv1/plugin/example/main.go	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5699      +/-   ##
==========================================
- Coverage   25.66%   25.66%   -0.01%     
==========================================
  Files         481      481              
  Lines       51244    51246       +2     
==========================================
  Hits        13151    13151              
- Misses      37095    37097       +2     
  Partials      998      998              

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[ffjlabo]

LGTM