R1:59ad78d4abc6

Improve package resolution APIs on CelerityResourceMap

Summary:
Ref T4222. A few diffs from now, `CelerityResourceMap` will have a `CelerityResources` inside of it:

- Rename `resolvePackage()` to `getResourceNamesForPackageHash()`. This isn't a functional change, it's just making it clear what it does.
- Add `getResourceDataForName()`, to push details about storage into `CelerityResources`.

Test Plan: Reloaded a bunch of pages, rebuilt map.

Reviewers: btrahan, hach-que

Reviewed By: hach-que

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