Get an already-known document by exact URI, or null.
Resolve an import specifier (e.g. Python "..utils.helpers") from a file
to a document — checking open models first, then asking the host's
loadFile hook. Returns null when nothing can provide the file.
Tracks open Monaco models and resolves import specifiers to documents.
Resolution order:
resolveModuleUrihook (when provided) supplies candidate URIs, otherwise built-in Python path heuristics compute them;loadFilehook — returned content becomes a real Monaco model so later navigation works natively.