test(signature): add two fuzz tests

[AdamKorcz]

Moves two fuzz tests upstream from here:

1. https://github.com/cncf/cncf-fuzzing/blob/main/projects/notary/fuzz_cose.go
2. https://github.com/cncf/cncf-fuzzing/blob/main/projects/notary/fuzz_jws.go

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.76%. Comparing base (0786f51) to head (f40cd1c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #229   +/-   ##
=======================================
  Coverage   91.76%   91.76%           
=======================================
  Files          30       30           
  Lines        2065     2065           
=======================================
  Hits         1895     1895           
  Misses        115      115           
  Partials       55       55           

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[shizhMSFT]

LGTM

[JeyJeyGao]

LGTM

[Two-Hearts]

LGTM

[priteshbandi]

LGTM

[priteshbandi]

@AdamKorcz can you please sign your commits?

[AdamKorcz]

@AdamKorcz can you please sign your commits?

It should already be signed by way of git commit -s. Is there another way, I should do it?

[Two-Hearts]

It should already be signed by way of git commit -s. Is there another way, I should do it?

@AdamKorcz The flag -s is for signoff. To fix, please try git commit --amend --no-edit -S --signoff. (note the capital S here).

[AdamKorcz]

git commit --amend --no-edit -S --signoff

Thank you! Done!