Performance: skip jsdoc parsing in various places

[dummdidumm]

May result in microscopic wins, every milisecond counts: microsoft/TypeScript#55739
Can use this in svelte2tsx, maybe other locations, too.
Usable in TS 5.3+

[dummdidumm]

Checked this, not sure if we can leverage this:

• svelte2tsx checks jsdoc for $props(), we may be able to omit this if we're checking if this is a JS file or not
• SvelteKit auto typings need it to adjust the imports, again we may be able to omit if we're checking if this is a JS file or not