fix: revert VersionReq being equal on inner RangeSet

[dsherret]

Reverts part of #13

Although it seemed like the right idea, the raw text is significant to know about in places like the LSP where we map the raw text back to the package requirement. If we make hashing and equals not based on the raw text, then these "duplicate" package requirements get lost in the npm resolution and it breaks some scenarios like auto-import mapping the version requirement text to a bare specifier in the import map when there are multiple possible version requirements for the same underlying RangeSetOrTag. In other words, the previous commit made us lose some resolution that we need for the LSP.

What we can do in the registry code that relied on this is to convert the VersionReqs into the inner RangeSetOrTags.

[dsherret]

I looked into this more on Luca's suggestion and it's actually a lot better to not keep around duplicate texts. Instead, we can go from the import map to a PackageReq, then do the comparison on the package reqs directly.