[PM-35680] chore: Convert SendClientProtocol to AutoMockable

[matt-livefront]

🎟️ Tracking

PM-35680

📔 Objective

Updates SendClientProtocol to AutoMockable.

[github-actions]

🤖 Bitwarden Claude Code Review

Overall Assessment: APPROVE

This PR converts the bespoke MockSendClient to an AutoMockable-generated MockSendClientProtocol, following the same pattern established in PR #2616. The change adds an empty SendClientProtocol extension to BitwardenSdkMocks.swift, removes duplicated hand-written mocks from both BitwardenShared and AuthenticatorShared test helpers, and updates SendRepositoryTests to use AutoMockable-generated properties (encryptReceivedSend, decryptReceivedSend, decryptCallsCount). Default closures in BitwardenShared's MockClientService preserve the prior round-trip encrypt/decrypt behavior so existing tests remain semantically equivalent.

Code Review Details

No findings.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.26%. Comparing base (1bc99e4) to head (4cef689).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2622      +/-   ##
==========================================
- Coverage   87.30%   86.26%   -1.05%     
==========================================
  Files        1900     2125     +225     
  Lines      169233   183729   +14496     
==========================================
+ Hits       147750   158489   +10739     
- Misses      21483    25240    +3757     

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