[Kernel] refactor 8bit quantization

[ZJY0516]

Purpose

Refactor the fp8 folder to 8bit, then includes fp8 and int8 folders

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
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[ZJY0516]

cc @yewentao256

[gemini-code-assist]

Code Review

This pull request refactors the quantization-related files by moving them into a new 8bit directory. While most of the changes are correct path updates, I've found several instances where the #include paths have been updated incorrectly. These new paths seem to assume that csrc is an include directory, which is inconsistent with other files in this pull request that use relative paths. This inconsistency will likely cause the build to fail. I've left specific comments with suggestions to fix these paths.

[yewentao256]

@ZJY0516 Thanks! We already have a PR for this #22474, pending for cutlass update from @mgoin

[ZJY0516]

Understood, thanks! I'll check for related PRs next time 😭