Deprecated internal PHP properties and constants

[ondrejmirtes]

phpstorm-stubs sometimes mark properties and constants as deprecated, but PHP reflection doesn't have methods to surface that information. Fortunately BetterReflection can surface that, although we might have to check method_exists before calling ->isDeprecated().

[ondrejmirtes]

Roave/BetterReflection#801

[eigan]

FILTER_SANITIZE_STRING was deprecated in 8.1 but is not reported.