feat: cache dirs::data_dir and dirs::cache_dir

[Myriad-Dreamin]

Intel vtune says dirs::data_dir and dirs::cache_dir make syscall on windows for each check existence of package files. This is a disaster on large packages.

With caching, the time used of tinymist query packageDocs --id @preview/cetz:0.2.2 goes down from 0.9s to 0.7s.

Intel vtune also says sys::stat syscall takes 0.2s to check existence of package files, but this need more careful cache strategy.

Though we currently don't response changes of these two cached directory paths, it is less likely to be changed in application wide.