Inherit ManagementApiClient to remove redundant initialization

[kailash-b]

Changes

ManagementClient previously implemented IManagementApiClient directly, duplicating every client property assignment that already exists in the generated ManagementApiClient. This meant any new endpoint added by code generation would break ManagementClient (missing property, broken interface) and call for manual updates.

What changed:

• ManagementClient now inherits from ManagementApiClient instead of implementing IManagementApiClient directly. All endpoint properties (Actions, Users, Organizations, etc.) are inherited automatically — keeping ManagementClient permanently in sync with generated code without any manual intervention.
• Added ManagementApiClient.Internal.cs (partial class) with an internal SetAuthorizationHeader(Func<Task<string>>) method. This is the minimal seam needed to wire the ITokenProvider dynamic token supplier into the RawClient headers post-construction, without modifying generated code.
• Constructor logic in ManagementClient refactored into two private static helpers (Validate, BuildClientOptions)

References

N/A

Testing

• This change adds unit test coverage
• This change adds integration test coverage
• This change has been tested on the latest version of the platform/language or why not

Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct
• All existing and new tests complete without errors

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.82%. Comparing base (9b23145) to head (397cd79).

Additional details and impacted files

@@            Coverage Diff             @@
##               v8     #936      +/-   ##
==========================================
- Coverage   33.89%   33.82%   -0.07%     
==========================================
  Files        1978     1979       +1     
  Lines       72861    72779      -82     
  Branches     4271     4269       -2     
==========================================
- Hits        24694    24620      -74     
+ Misses      46947    46939       -8     
  Partials     1220     1220              

Flag	Coverage Δ
authIntTests	4.11% <95.23%> (+0.04%)	⬆️
mgmtIntTests	32.11% <100.00%> (-0.07%)	⬇️
unittests	0.43% <0.00%> (+<0.01%)	⬆️

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