[MLIR][CODEOWNERS] Add XeGPU and XeVM codeowners

[silee2]

XeGPU and XeVM dialect has assigned maintainers, but related folders currently lack code owners.
Add charithaintc and Jianhui-Li as code owner for XeGPU related folders.
Add silee2 as code owner for XeVM related folders.
Note:
charithaintc is current maintainer of XeGPU dialect.
silee2 is current maintainer of XeVM dialect.

[silee2]

@rengolin Who should I ask for review? Surprised to see no code owner assigned for CODEOWNERS file.

[silee2]

@tkarna I cannot add you as a reviewer. Do you lack write permit?

[tkarna]

@tkarna I cannot add you as a reviewer. Do you lack write permit?

That's right, my commit access request is still pending. This looks good to me, but I'm not sure if I can be marked as a codeowner before I have permissions.

[rengolin]

@rengolin Who should I ask for review? Surprised to see no code owner assigned for CODEOWNERS file.

This is mostly self-assigned. It only means "I want to receive notifications for PRs and issues on those areas".

I have approved.

[silee2]

@tkarna I cannot add you as a reviewer. Do you lack write permit?

That's right, my commit access request is still pending. This looks good to me, but I'm not sure if I can be marked as a codeowner before I have permissions.

I'll remove for now and can add you later once you get write permit.