Fix handling of dynamic constants

[IanDelMar]

This PR improves the handling of dynamic constants by adding those defined in bootstrap.php to the dynamicConstantNames list in extension.neon. This change ensures that PHPStan generalises the types of these constants. In particular, for directory constants, this prevents the RequireFileExistsRule from reporting errors about non-existent WordPress core files.

Regarding WP_DEBUG_LOG: although it is currently generalised to bool, it may in fact hold either a boolean or a string value. Including define('WP_DEBUG_LOG', true); incorrectly narrows its type to bool. However, PHPStan does not currently support dynamic constants with multiple types. Removing WP_DEBUG_LOG from bootstrap.php would result in constant.notFound errors being reported. As no users have reported issues with the current type, it has been retained for the time being.

Furthermore, this PR begins to use WordPress’s actual default values (see discussion).

I have added "tests" (see commit dbbd206); however, these serve mainly to demonstrate PHPStan’s behaviour, rather than testing the functionality of this extension itself. For this reason, I would recommend removing them prior to merging.

Fixes #282, fixes #239
Closes #283
Related #239

[szepeviktor]

I need comments to merge this.

[IanDelMar]

Sure! This PR still needs some tests anyway, hence it’s a draft.

[szepeviktor]

I mean comments from others.

[IanDelMar]

Yes, I had already understood you meant comments from others.

[slaFFik]

LGTM :)