purl-next: Update the PURL library for Python with extended validation - batch 1

[pombredanne]

Update the PURL library for Python with extended syntax and content validation checks created for supported ecosystems - batch 1

• alpm
• apk
• bitbucket
• bitnami
• cocoapods
• cargo
• composer
• conan
• conda
• cran
• deb
• docker
• gem
• generic
• github
• golang

[TG1999]

Add a validate method for a PackageURL object, it will yield the error messages as in: https://github.com/aboutcode-org/scancode-toolkit/blob/c9015f8bf3974e11c5997ebba882d65985a0b6f4/src/licensedcode/models.py#L1912

The validation should come from the JSON type definition, like for cargo: https://github.com/package-url/purl-spec/blob/main/types/cargo-definition.json

For cargo having a namespace is an error for example

[pombredanne]

This has been completed and merged with:

• Add validation function package-url/packageurl-python#205