chore: remove deprecated multicodec package

[nickreynolds]

What issue is this PR fixing

removes multicodec package which was deprecated and refactors bytesToMultibase util function to support secp256k keys

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]

Codecov Report

Patch coverage: 57.14% and project coverage change: -0.04% ⚠️

Comparison is base (e2efa88) 84.92% compared to head (8307cd7) 84.88%.

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #1245      +/-   ##
==========================================
- Coverage   84.92%   84.88%   -0.04%     
==========================================
  Files         167      167              
  Lines       18120    18120              
  Branches     2036     2040       +4     
==========================================
- Hits        15388    15382       -6     
- Misses       2732     2738       +6     

Files Changed	Coverage Δ
packages/utils/src/encodings.ts	88.71% <50.00%> (-2.35%)	⬇️
...ackages/did-provider-peer/src/peer-did-provider.ts	64.28% <60.00%> (-1.39%)	⬇️
packages/did-provider-key/src/key-did-provider.ts	76.92% <100.00%> (-0.53%)	⬇️

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