AMDGPU: harden hotswap ELF growth and descriptors

[harsh-amd]

Stacked on #3138.

Summary:

• Key entry trampoline descriptor rewrites by descriptor virtual address so duplicate kernel descriptor names update the intended descriptor.
• Make SGPR metadata fallback explicit: missing or malformed per-kernel SGPR metadata logs a warning and falls back to the descriptor, while corrupt metadata remains a hard error.
• Keep descriptor SGPR fields in sync with the effective metadata count.
• Adjust grown ELF sections, program headers, and symbols using virtual-address ordering while preserving file-offset movement by file order.
• Keep debug symbol/line trampoline inputs limited to B0/A0 trampolines while shifting debug addresses by total .text growth.

Tests:

• build/bin/HotswapElfTests
• build/bin/HotswapMCTests
• build/bin/llvm-lit -sv build/tools/comgr/test-lit --filter hotswap
• build-asan/bin/HotswapElfTests
• build-asan/bin/HotswapMCTests
• build-asan/bin/llvm-lit -sv build-asan/tools/comgr/test-lit --filter hotswap