[CK_TILE] Share partition index across threads and specify offset in load_tile()/async_load_tile()/load_tile_transpose()

[poyenc]

Proposed changes

1. Allow specifying a partition index for the tile_window_with_static_distribution<> template, with the resulting offset applied as an immediate offset in the instructions.
2. Allow specifying an additional offset for the load_tile(), async_load_tile() and load_tile_transpose() calls to ensure that each thread reads the correct data, even when sharing the same partition index.
3. Use warp-uniform LDS offset in tile_window::async_load() to avoid unnecessary VOPs and readfirstlane

Checklist

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• I have added tests relevant to the introduced functionality, and the unit tests are passing locally
• I have added the test to REGRESSION_TESTS list defined at the top of CMakeLists.txt in tests/CMakeLists.txt, IF the test takes more than 30 seconds to run.
• I have added inline documentation which enables the maintainers with understanding the motivation
• I have removed the stale documentation which is no longer relevant after this pull request
• (If this change is user-facing) I have added release notes which provide the end users with a brief summary of the improvement from this pull request
• I have run clang-format on all changed files
• Any dependent changes have been merged

Discussion

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