feat: Added trustpolicy and truststore packages under verification

[patrickzheng200]

PR review order: #190 -> This PR -> #191 -> #186

This PR adds the trustpolicy and truststore packages under verification.

Signed-off-by: Patrick Zheng [email protected]

[codecov-commenter]

Codecov Report

Merging #192 (7e79d10) into main (49ba3a3) will decrease coverage by 1.43%.
The diff coverage is 79.19%.

@@            Coverage Diff             @@
##             main     #192      +/-   ##
==========================================
- Coverage   80.78%   79.34%   -1.44%     
==========================================
  Files          22       24       +2     
  Lines        1717     1951     +234     
==========================================
+ Hits         1387     1548     +161     
- Misses        258      319      +61     
- Partials       72       84      +12     

Impacted Files	Coverage Δ
verification/verifier.go	83.33% <ø> (ø)
verification/verifier_helpers.go	68.96% <ø> (ø)
registry/repository.go	33.84% <34.04%> (-57.70%)	⬇️
verification/truststore/truststore.go	52.94% <52.94%> (ø)
verification/trustpolicy/trustpolicy.go	96.10% <96.10%> (ø)

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[priteshbandi]

LGTM

[shizhMSFT]

LGTM