Rename and deprecated rfc8888 package

[mengelbart]

Rename rfc8888 packages. We don't have any other packages named after the respective RFCs.

[codecov]

Codecov Report

❌ Patch coverage is 7.69231% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.29%. Comparing base (a8ad680) to head (a3df37e).

Files with missing lines	Patch %	Lines
pkg/rfc8888/rfc8888.go	0.00%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #351      +/-   ##
==========================================
- Coverage   81.54%   81.29%   -0.26%     
==========================================
  Files          90       91       +1     
  Lines        4671     4683      +12     
==========================================
- Hits         3809     3807       -2     
- Misses        683      696      +13     
- Partials      179      180       +1     

Flag	Coverage Δ
go	81.29% <7.69%> (-0.26%)	⬇️

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[JoTurk]

I think we can ignore the API check this time, since interceptor is v0 and I think this change is compatible enough.

[mengelbart]

Sounds good, I'll merge it now. Sorry, I didn't merge it earlier. I kind of lost track of this.