fix: convert to peer schema with multiple protocols

[hacdias]

Makes the /routing/v1/providers endpoint comply with the Peer Schema: https://specs.ipfs.tech/routing/http-routing-v1/#peer-schema

I changed all the current providers since they're all technically peers. Also note that I changed the protocol string to an array since we now send all protocols for the same peer in the same record. The metadata is implemented per protocol, hence a custom MarshalJSON.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 30 lines in your changes are missing coverage. Please review.

Project coverage is 7.21%. Comparing base (1298b7d) to head (6d44b74).
Report is 2 commits behind head on main.

Files	Patch %	Lines
delegated_translator.go	0.00%	30 Missing ⚠️

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Additional details and impacted files

@@           Coverage Diff            @@
##            main    #185      +/-   ##
========================================
+ Coverage   6.66%   7.21%   +0.54%     
========================================
  Files         11      11              
  Lines       1380    1165     -215     
========================================
- Hits          92      84       -8     
+ Misses      1281    1074     -207     
  Partials       7       7              

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