fix(credential-ld): let verifiers use all supported verification methods

[mirceanis]

What issue is this PR fixing

fixes #1329

What is being changed

The VeramoLdSignature.getSupportedVerificationType() can now return string[] as well as string
This allows VeramoLdSignature suite implementations to signal compatibility with multiple Verification Method types for verification.

Quality

Check all that apply:

• I want these changes to be integrated
• I successfully ran pnpm i, pnpm build, pnpm test, pnpm test:browser locally.
• I allow my PR to be updated by the reviewers (to speed up the review process).
• I added unit tests.
• I added integration tests.
• I did not add automated tests because _________, and I am aware that a PR without tests will likely get rejected.

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (7896cea) 89.83% compared to head (cde68aa) 89.83%.

Files	Patch %	Lines
...s/credential-ld/src/suites/JsonWebSignature2020.ts	66.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             next    #1331   +/-   ##
=======================================
  Coverage   89.83%   89.83%           
=======================================
  Files         176      176           
  Lines       27010    27017    +7     
  Branches     2120     2124    +4     
=======================================
+ Hits        24265    24272    +7     
  Misses       2745     2745           

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