Remove TypeScript moving parts

[johnsoncodehk]

Initial checklist

• [x] I read the support docs
• [x] I read the contributing guide
• [x] I agree to follow the code of conduct
• [x] I searched issues and discussions and couldn’t find anything or linked relevant results below
• [x] I made sure the docs are up to date
• [x] I included tests (or that’s not needed)

Description of changes

When MDX TypeScript support is already provided through the TS plugin, the language server's TypeScript moving parts seem unnecessary, and I think it can be removed along with the tsdk option to simplify IDE integration.

• The tsdk option no longer needs to be passed by the language client, but is more simply added to the peerDependencies
• The language server TS tests need to be re-implemented based on @typescript/server-harness, which can be found at https://github.com/vuejs/language-tools/blob/master/packages/language-server/tests
• When language server doesn't need TS support, the file watcher doesn't seem to be needed anymore.
• I'm not sure if markPlugins, virtualCodePlugins are useful when language server doesn't need TS support. If it is, we need to refer to https://github.com/vuejs/language-tools/blob/073a7cb3bb823479ae5e9bff52850f529714571d/packages/language-server/index.ts#L62 to find tsconfig for each MDX file.