Fix duplicate count constants and globals

[kkmuffme]

• don't count undocumented globals (as duplicate) when only including documented globals and vice versa
• don't cound constants "in if" as duplicates
• only include documented globals if their docblock contains an @var (or their @psalm/@phpstan equivalent), as otherwise the doc comment (and global) is irrelevant for the stubs - in fact it's often a false positive caused by other annotations (e.g. @package or in WordPress @param for apply_filters assignments)
• add tests to ensure constants documented in the "define" like define( 'FOOBAR', /** @var int */ 0 ); continue to be correctly added to stubs