[Refactoring]Remove XeTile dialect from IMEX project

[Garra1980]

  - Removed all XeTile test directories (117 test files)
  - test/Dialect/XeTile/ (39 files)
  - test/Conversion/XeTileToXeGPU/ (18 files) - test/Integration/Dialect/XeTile/ (60+ files) - test/Transforms/InsertGpuAllocs/add-gpu-alloc-xetile.mlir

- Removed XeTile core dialect and conversion directories - include/imex/Dialect/XeTile/ (entire directory) - lib/Dialect/XeTile/ (entire directory) - include/imex/Conversion/XeTileToXeGPU/ (entire directory) - lib/Conversion/XeTileToXeGPU/ (entire directory)

- Updated CMake build configuration (5 files)
  - Removed add_subdirectory(XeTile) from lib/Dialect/CMakeLists.txt
  - Removed add_subdirectory(XeTile) from include/imex/Dialect/CMakeLists.txt - Removed add_subdirectory(XeTileToXeGPU) from lib/Conversion/CMakeLists.txt - Removed 3 XeTile library references from lib/CAPI/CMakeLists.txt

- Updated registration headers (3 files) - Removed XeTile include and dialect registration from InitIMEXDialects.h - Removed XeTile pass registration from InitIMEXPasses.h - Removed XeTileToXeGPU include from Conversion/Passes.h - Removed XeTileToXeGPU pass definition from Conversion/Passes.td

- Cleaned utility files of XeTile dependencies
  - Removed XeTile include from lib/Utils/XeCommon.cpp
  - Removed isSupportedOptimalSLMAccess() function - Simplified isSupportedModule() (XeTile checks removed) - Removed XeTile handling from lib/Transforms/InsertGPUAllocs.cpp

- Updated header files (5 files) - Removed XeTile include from include/imex/Utils/XeCommon.h - Removed TileUsageAnalysis class (145 lines) - Removed isSupportedOptimalSLMAccess() declaration - Removed XeTile includes from XeGPUToVC.h and XeArch.h

- Removed documentation and scripts
  - docs/rfcs/XeTile.md
  - scripts/xetile-test-gen/ (entire directory)

Total: 167 files changed
Result: Clean IMEX repository without XeTile dependencies
Build verification: CMake configuration successful, no XeTile-related errors

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