Fix case-parsing for "new" npm packages

[sschuberth]

Currently, packageurl-js package parses the name of an npm package from the purl case-sensitively only in specific cases for some legacy npm packages. (Thanks @lamppu for the analysis.)

See:

packageurl-js/src/purl-type.js

Lines 139 to 143 in bb4185a

	// Ignore lowercasing legacy names because they could be mixed case.
	// https://github.com/npm/validate-npm-package-name/tree/v6.0.0?tab=readme-ov-file#legacy-names
	if (!isNpmLegacyName(getNpmId(purl))) {
	lowerName(purl)
	}

According to this discussion in this purl-spec issue that conditional behavior seems to be wrong, and mixed case packages should be unconditionally allowed (see the last comment from @pombredanne).

@jdalton, do you think a fix and release would be doable soon?