purl-next: Support updated spec in packageurl-java

[pombredanne]

Adopt and implement updated spec in PURL libraries working with their maintainers.

[TG1999]

PR in progress:

• test: Run tests using reference data from purl-spec package-url/packageurl-java#252

[keshav-space]

Completed in aboutcode-org/packageurl-java#2

Out of 618 tests, 26 are failing: ~96% test are passing
Most of these failures are related to bugs in the test fixtures, and some are case where the purl parsing should fail but packageurl-java handles it anyway.