fix(lsp): handle importmaps properly

[kitsonk]

This fixes several issues with import maps and the language server:

• When the import map was updated, dependencies were not recalculated, meaning changes the open documents were required to "update" the files.
• Non-open resources did not actually have import maps applied to them, which resulted in situations where types "corrected themselves" when opening documents in the editor.
• Open documents in the editor didn't use the language ID, instead inferred the type from the module specifier, which is an imprecise way of determining the type of the file.

Fixes: #11146
Fixes: #11456
Fixes: #10439

[bartlomieju]

LGTM, nice fix