Remove decl_collector pass and use SWC's unresolved_mark instead

[devongovett]

The decl_collector pass stored all declarations in a HashSet so we could determine if a variable is a global (i.e. undeclared). This is used to find require calls and much more. Turns out we don't really need this anymore because SWC has an unresolved_mark that it sets on these identifiers in its resolver. Removing this saves us a pass, reduces some memory usage, and simplifies the code by reducing the number of places we need to keep up to date.

[mischnic]

Are we sure this is always correct? I just remember the multiple times where swc's unresolved and global mark don't really do what they say they do: #8151 and #8029

[devongovett]

I think it may have been improved. I noticed that SWC's minifier and Turbopack both use this same check. I did also try to remove the second pass of the resolver after preset env that you added before as well, but that was still broken. Otherwise it seems to pass all of our tests here and we can test on some apps too.