Add PHP 8.4 to CI

Add extra keywords to PHP dictionary

Add phpstan

Expose Config class

This is the public API from the perspective of fuzzing targets,
and should be exposed.

It might make sense to just expose the entire PhpFuzzer namespace,
as the main purpose of the scoping is to avoid collisions with
other uses of PhpParser.

Fixes #7.

Support mutation depth during minimization

Multiple mutations may be necessary to achieve a shorter crashing
input.

Update to PHPUnit 9

Catch fatal errors on shutdown

Don't intercept phar:// streams

This runs into issues with error handling during path resolution.
Fixed upstream in php/php-src@003be87,
but for now just disable this part, as we don't really need it
anyway.

Remove realpath() calls used to work around interceptor bug

Add some technical notes