feat: drop methods for finding keys by public/private prefix

[aarmam]

Drop FindKeyByPrefix/FindKeysByPrefix methods for finding keys by public/private prefix and use FindPublicKey/FindPrivateKey helper methods instead.

Related issue(s)

This feature is continuation of #2758

It is also related to #2625 where it would be easer to review it, if suggest this change separately.
In short to find keypairs from HSM I use attribute CKA_LABEL as key set id and CKA_ID as key id and they have to be 1:1 for pub/priv keys:
https://github.com/ThalesIgnite/crypto11/blob/master/keys.go#L247-L278

This helps me to get rid of https://github.com/aarmam/hydra/blob/feature/hsm/hsm/manager_hsm.go#L243-L261 where I prefix keys manually altough key id's on HSM are without prefixes.

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[codecov]

Codecov Report

Merging #2814 (c1fb80d) into master (f15f339) will decrease coverage by 0.13%.
The diff coverage is 36.14%.

@@            Coverage Diff             @@
##           master    #2814      +/-   ##
==========================================
- Coverage   49.87%   49.74%   -0.14%     
==========================================
  Files         236      236              
  Lines       14974    15032      +58     
==========================================
+ Hits         7469     7477       +8     
- Misses       6843     6890      +47     
- Partials      662      665       +3     

Impacted Files	Coverage Δ
client/client.go	81.25% <ø> (ø)
consent/manager.go	100.00% <ø> (ø)
consent/handler.go	63.57% <18.75%> (-1.76%)	⬇️
consent/strategy_default.go	67.34% <26.66%> (-2.37%)	⬇️
persistence/sql/persister_consent.go	73.99% <40.00%> (-4.42%)	⬇️
consent/manager_test_helpers.go	97.50% <100.00%> (ø)

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