feat: create pluggable CredentialService url resolver

[paullatzelsperger]

What this PR changes/adds

This PR adds a pluggable CredentialServiceUrlResolver, whos job it is to take an issuer, and resolve its CredentialService URL.
The default implementation in IATP for this will be a DidCredentialServiceUrlResolver, that interprets the issuer as DID and
resolves the DID, which is expected to contain a CredentialService endpoint entry.

Why it does that

The relying party (RP) needs to be able to resolve the counter-party's CredentialService to obtain VCs.

Further notes

List other areas of code that have changed but are not necessarily linked to the main feature. This could be method
signature changes, package declarations, bugs that were encountered and were fixed inline, etc.

Linked Issue(s)

Closes #3647

Please be sure to take a look at the contributing guidelines and our etiquette for pull requests.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (906bc17) 71.74% compared to head (f2a8bfd) 71.76%.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3654      +/-   ##
==========================================
+ Coverage   71.74%   71.76%   +0.02%     
==========================================
  Files         915      916       +1     
  Lines       18342    18356      +14     
  Branches     1040     1041       +1     
==========================================
+ Hits        13159    13173      +14     
  Misses       4727     4727              
  Partials      456      456              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.