Improve on laziness of package metadata reading during LSP startup

[DavisVaughan]

i noticed that test_rename_to_empty_name_returns_clean_error runs quite slow for me (like 5 seconds or so most of the time when the test is run in debug mode, the default)

it looks like set_library_paths -> scan_new_library_path can take a loooooooong time when you have quite a few packages, like 600 of them 😬

it does run faster in release mode, i.e. just test test_rename_to_empty_name_returns_clean_error --release runs in more like 1 second.

the problem seems to mostly be Air's parsing of 600 package NAMESPACE files, which I think we can probably do lazily and delay until required.

[DavisVaughan]

Maybe namespace can be a query on Package rather than a field? With a tracked result?

ark/crates/oak_db/src/inputs.rs

Line 201 in b7eb74e

pub namespace: Namespace,

[lionel-]

yep namespace and version, this way we don't read DESCRIPTION either. The only thing that need to know eagerly are the names of installed packages, which in well-formed libraries can be inferred from the folder names.