refactor!: remove blob sign/verify for v1.3.0-rc.1 release

[Two-Hearts]

This PR is for release-1.3 branch.

It removes the blob sign/verify from this version. The commit is cherry picked from what we had in v1.2.

[codecov]

Codecov Report

Attention: Patch coverage is 89.47368% with 4 lines in your changes missing coverage. Please review.

Project coverage is 81.71%. Comparing base (84c2ec0) to head (b9e098b).
Report is 1 commits behind head on release-1.3.

Files with missing lines	Patch %	Lines
verifier/verifier.go	82.35%	2 Missing and 1 partial ⚠️
verifier/trustpolicy/oci.go	95.23%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           release-1.3     #464      +/-   ##
===============================================
+ Coverage        81.34%   81.71%   +0.37%     
===============================================
  Files               34       33       -1     
  Lines             2578     2374     -204     
===============================================
- Hits              2097     1940     -157     
+ Misses             335      302      -33     
+ Partials           146      132      -14     

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[shizhMSFT]

LGTM

[shizhMSFT]

Other maintainers may take a look at https://github.com/notaryproject/notation-go/compare/v1.2.1..b9e098b21ddbd1f0426a094458e9e7bf5a434d75 for faster review.

[priteshbandi]

LGTM