Make host target tracing implementation headers private

[coado]

Summary:
Mark the following headers as private instead of for-frameworks. All of them are implementation details of how the host target records and serializes a trace, and no for-frameworks header includes them:

• HostTracingProfileSerializer transforms a HostTracingProfile into serialized trace events. It is only used by its own source and HostTargetTracing.h.
• HostTargetTracing.h provides emitNotificationsForTracingProfile, which uses the serializer to send a captured profile to frontend channels as Tracing.dataCollected events followed by Tracing.tracingComplete. It is only used by HostTarget.cpp and TracingAgent.cpp, and was already not exported in Buck.
• HostTargetTraceRecording holds the state of an in-progress host trace recording. HostTarget.h only forward-declares it, and it is only used by HostTarget.cpp, HostTargetTraceRecording.cpp and HostTargetTracing.cpp.
• TimeWindowedBuffer is a generic buffer that keeps only elements inside a time window. It is only used by HostTargetTraceRecording and its own unit test.
• TracingAgent handles the CDP Tracing.start and Tracing.stop requests for the host agent. It is only used by HostAgent.cpp and TracingAgent.cpp, and was already not exported in Buck.

Headers that include one another change together: HostTargetTracing.h includes HostTracingProfileSerializer.h, and HostTargetTraceRecording.h stores a TimeWindowedBuffer by value, so keeping either includer for-frameworks would expose a private header. HostTracingProfile.h, FrameTimingSequence.h, TraceRecordingState.h and TracingCategory.h stay for-frameworks because other for-frameworks headers include them.

React Native's own targets define RN_BUILDING, so the private guard does not affect them.

Changelog: [Internal]

Differential Revision: D122791607

[meta-codesync]

@coado has exported this pull request. If you are a Meta employee, you can view the originating Diff in D122791607.