XLA documentation for Windows

[mraunak]

Recently, we added a configuration to enable XLA on the Windows platform(#11299). Next, to provide comprehensive guidance on building XLA from source and running XLA test cases on Windows, we need to update the documentation to include detailed instructions for setting up the necessary dependencies and environment variables.

Proposed Changes:

Installation of Required Dependencies:
BAZEL: Provide clear steps for installing Bazel on the Windows platform.
MYSYS: Detail the installation process for MSYS, ensuring compatibility with the build environment.
LLVM CLANG COMPILER: Include instructions for installing the LLVM Clang Compiler, specifying the supported version.

Setting Up Environmental Variables:
Guide users through the process of setting up environmental variables required for XLA compilation and execution

Test Case Execution Instructions and Troubleshooting Guidance

[learning-to-play]

Hi @ddunl , Where should @mraunak add the documentation?