typescript: Improve installation checks for `vtsls` (#20197)

This PR improves the installation checks for `vtsls`.

Previously we were checking the installed version of TypeScript against
the latest available version to determine whether we needed to installed
the `vtsls` language server or not.

However, these are two independent concerns, so we should be checking
individually whether `typescript` or `@vtsls/language-server` need to be
installed/updated.

Closes https://github.com/zed-industries/zed/issues/18349.

Release Notes:

- typescript: Fixed an issue where `@vtsls/language-server` may not have
been updated to the latest version.