* Update GitHub.Copilot.SDK to 0.1.23 and copy new session config properties
- Bump GitHub.Copilot.SDK from 0.1.18 to 0.1.23
- Add new SessionConfig properties: ReasoningEffort, Hooks, OnUserInputRequest,
WorkingDirectory, ConfigDir, InfiniteSessions
- Add missing ResumeSessionConfig properties: Model, SystemMessage,
AvailableTools, ExcludedTools, ReasoningEffort, Hooks, OnUserInputRequest,
WorkingDirectory, ConfigDir, InfiniteSessions
- Fix UserMessageDataAttachmentsItem -> UserMessageDataAttachmentsItemFile
for new polymorphic attachment API
- Add unit tests for new session config properties
* Address PR review: centralize config mapping and improve test coverage
- Extract CopySessionConfig/CopyResumeSessionConfig as internal static helpers
to eliminate duplicated mapping logic between RunCoreStreamingAsync and
CreateResumeConfig (addresses reviewer comment on drift risk)
- Add InternalsVisibleTo for unit test project
- Replace shallow constructor tests with comprehensive property-verification
tests that validate every config property is correctly copied, including
OnUserInputRequest (addresses reviewer comments on test coverage)
* Remove accidentally committed git-lfs hooks