Preserve case on npm package requests

https://issues.sonatype.org/browse/NX-633

I'm not sure if this is the best way to fix this, so this PR is more to start a discussion on how we want to deal with this. Here is a summary of the problem:

The package metadata that we pull from the registry root is case-sensitive (e.g. StringScanner). However, when a package request comes in, we convert it to lowercase before looking up the metadata. So this fails for packages that contain any capital letters (e.g. StringScanner).

We either need to convert everything to lower case before storing the metadata, or stop converting package requests to lowercase, which is the simple change that I opted for to test this out.

If we decide to stick with this change, the PackageCoordinatesTest.coordinatesFromUrl_CaseDoesNotMatter test will need to be updated.