Added ClientScope ProtocolMappers CRUD

[HimanshuM]

This PR adds ability to add, modify or remove protocol mappers under a client scope in Keycloak.

[Nerzal]

Hi!
Thank you for the contribution!

Could you please try and update your branch using the current main branch?
That should fix the CI Pipeline :)

[HimanshuM]

Thanks for your response @Nerzal I have merged main into my fork.

[codecov]

Codecov Report

Merging #351 (1636b01) into main (289eed6) will increase coverage by 0.07%.
The diff coverage is 81.25%.

@@            Coverage Diff             @@
##             main     #351      +/-   ##
==========================================
+ Coverage   76.78%   76.85%   +0.07%     
==========================================
  Files           4        4              
  Lines        1973     2005      +32     
==========================================
+ Hits         1515     1541      +26     
- Misses        317      320       +3     
- Partials      141      144       +3     

Impacted Files	Coverage Δ
client.go	75.17% <81.25%> (+0.10%)	⬆️

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[Nerzal]

Thank your for the contribution, now merging :)

I'll wait some more hours, before i create a new release, as we might get another PR merged today :)