Document Linux-specific C++ components in Service Fabric

[Copilot]

Analysis of Linux-specific C++ components across the Service Fabric codebase. Adds docs/linux-cpp-components.md cataloging ~204 files.

Components Identified

• Explicitly named Linux files (77): *.Linux.cpp, *Linux*.cpp across Common, Hosting2, Transport, HttpTransport, Store, httpgateway
• PAL (Platform Abstraction Layer) (105): Windows API emulation in src/prod/src/pal/src/ - covers wincrypt, winsock2, winreg, security, COM, etc.
• Lease layer Linux impl (16): Complete implementation in src/prod/src/Lease/linux/
• KTL components (11+): LTTNG tracing, KXM kernel extension modules, logger tests

Key Subsystems

Subsystem	Linux Support
Common	Crypto, file monitoring, threadpool, XML, timers
Hosting2	Process activation, containers, IPAM, overlay networking
Transport	Socket listeners, SSL security context
Store	Azure storage client
KTL	LTTNG integration, KXM user-mode bridge

Files using #if defined(PLATFORM_UNIX) conditionals are also documented but not exhaustively listed.

Original prompt

Identify all linux specific components written in c++

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