feat: make image spec preview

[wangxiaoxuan273]

What this PR does / why we need it:
make --image-spec [Preview] from [Experimental].

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Part of #1274

Please check the following list:

• Does the affected code have corresponding tests, e.g. unit test, E2E test?
• Does this change require a documentation update?
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have an appropriate license header?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.35%. Comparing base (9732d14) to head (c9b088d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1338      +/-   ##
==========================================
- Coverage   84.40%   84.35%   -0.06%     
==========================================
  Files         101      101              
  Lines        3617     3617              
==========================================
- Hits         3053     3051       -2     
- Misses        335      337       +2     
  Partials      229      229              

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[qweeah]

LGTM