Add Admin::DomainAllow methods

[G10xy]

Description

This PR implements the domain allows API so that users with role of admin to both see allowed federated domains, remove allowed domain and add new domain to be federated.

This closes #328

Type of Change

• New feature

How Has This Been Tested?

Gradle ktlint, gradle check, gradle detect and gradle build

Mandatory Checklist

• I ran gradle check and there were no errors reported
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or that my feature works
• All tests pass locally with my changes
• I have added KDoc documentation to all public methods

Optional checks

I implemented related RX counter part and implemented unit test.
I also updated the API coverage page with corresponding ones developed in this PR.

[codecov]

Codecov Report

Attention: 21 lines in your changes are missing coverage. Please review.

Comparison is base (90c8259) 49.84% compared to head (107a6c6) 49.86%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #413      +/-   ##
============================================
+ Coverage     49.84%   49.86%   +0.02%     
- Complexity      661      668       +7     
============================================
  Files           162      165       +3     
  Lines          4484     4528      +44     
  Branches        284      284              
============================================
+ Hits           2235     2258      +23     
- Misses         1996     2016      +20     
- Partials        253      254       +1     

Files	Coverage Δ
...e/src/main/kotlin/social/bigbone/MastodonClient.kt	35.45% <100.00%> (+0.16%)	⬆️
...igbone/api/method/admin/AdminDomainBlockMethods.kt	60.78% <100.00%> (ø)
...igbone/api/method/admin/AdminDomainAllowMethods.kt	95.00% <95.00%> (ø)
...ocial/bigbone/api/entity/admin/AdminDomainAllow.kt	33.33% <33.33%> (ø)
...cial/bigbone/rx/admin/RxAdminDomainAllowMethods.kt	0.00% <0.00%> (ø)

[PattaFeuFeu]

Looking mostly good! Thanks for your contribution 🙌

[PattaFeuFeu]

Thanks for the updates! 😊 🚀