Match redundant @param docblocks across union order and FQN vs short name

[TomasVotruba]

Removing a redundant @param tag only fired when its type text matched the added native type character for character. Two common shapes were missed:

• union members in a different order, e.g. @param string|array vs array|string
• an imported short name vs a fully qualified union member, e.g. @param CompositeExpression|string vs \Doctrine\DBAL\Query\Expression\CompositeExpression|string

normalizeDocType now reduces each union member to its last name part and sorts them, so both sides compare equal and the tag is dropped.

Covered by two new cases in docparam_test.go.