Improve tests & Fix CNAME support

[BeryJu]

closes #838

CNAME support had been improved in etcd for a bit but this PR adds the same logic to the memory handler and dedupes a bunch of code

Also for tests, replaces the network communication with a much stricter direct query

[netlify]

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Name	Link
🔨 Latest commit	94ee623
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[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 23.18%. Comparing base (d11ac22) to head (94ee623).

Files	Patch %	Lines
pkg/roles/api/role.go	0.00%	2 Missing ⚠️
pkg/roles/dns/handler_etcd.go	88.88%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1033      +/-   ##
==========================================
- Coverage   23.51%   23.18%   -0.33%     
==========================================
  Files         215      214       -1     
  Lines       15661    15643      -18     
==========================================
- Hits         3682     3627      -55     
- Misses      11554    11590      +36     
- Partials      425      426       +1     

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