Make IsSSFlagEnabled signature consistent across all architectures

[Copilot]

Summary

IsSSFlagEnabled had inconsistent signatures across architectures:

• AMD64 / i386: inline bool IsSSFlagEnabled(DT_CONTEXT * context) — 1 parameter (context only)
• ARM64: same 1-param inline in header, plus a 2-param declaration in arm_primitives.h (two overloads)
• ARM / LOONGARCH64 / RISCV64: bool IsSSFlagEnabled(DT_CONTEXT *pCtx, Thread *pThread) — 2 parameters

This forced call sites in debugger.cpp to use awkward ARM_ARG(pThread) ARM64_ARG(pThread) RISCV64_ARG(pThread) LOONGARCH64_ARG(pThread) macros to conditionally pass the thread.

Changes

All architectures now use a uniform signature: bool IsSSFlagEnabled(DT_CONTEXT *pCtx, Thread *pThread). Architectures that don't need the Thread* parameter (AMD64, i386, ARM64 without FEATURE_EMULATE_SINGLESTEP) simply ignore it.

• debug/inc/amd64/primitives.h and debug/inc/i386/primitives.h: Added class Thread; forward declaration and Thread* /* pThread */ = nullptr parameter to the inline function. Consistent with the same pattern already used in arm/primitives.h, loongarch64/primitives.h, etc.
• debug/inc/arm64/primitives.h: Removed the 1-param IsSSFlagEnabled inline. The 2-param declaration from the already-included arm_primitives.h now serves as the sole declaration.
• debug/ee/arm64/primitives.cpp: In the !FEATURE_EMULATE_SINGLESTEP block, replaced return IsSSFlagEnabled(pContext) (which called the now-removed 1-param inline) with the CPSR check directly.
• debug/di/arm64/primitives.cpp: Added a !FEATURE_EMULATE_SINGLESTEP implementation of IsSSFlagEnabled for Windows ARM64 DBI (which has FEATURE_INTEROP_DEBUGGING but not FEATURE_EMULATE_SINGLESTEP).
• debug/di/rsthread.cpp: Updated 5 call sites to pass nullptr as the thread.
• debug/di/process.cpp: Updated 2 call sites to pass nullptr as the thread.
• debug/ee/debugger.cpp: Simplified the macro-based call to always pass pThread directly.

Note

SetSSFlag and UnsetSSFlag have the same signature inconsistency. That cleanup can be done as a follow-up.

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[davidwrighton]

Sigh. This doesn't actually look better.