Preg match regex mutators #2

[maks-rafalko]

This PR is a rebirth of #388

Fixes #324

• took @adeptofvoltron's work
• fixed all comments and adopted to the current code base
• added more tests
• Doc PR: Add docs for new regex mutators site#203

2 new mutations here:

# 1
- preg_match("/^test$/", $string));
+ preg_match("/^test/", $string));

# 2
- preg_match("/^test$/", $string));
+ preg_match("/test$/", $string));

Other possible mutations will be done in a separate PRs after this one is merged.

[maks-rafalko]

Unfortunately, thecodingmachine/safe package does not support Psalm's annotations yet, and functions are missing @pure annotation, that's why we have issues reported by Psalm.

Tried https://github.com/hectorj/safe-php-psalm-plugin, but it doesn't work properly, so for now it's ok to suppress them

[BackEndTea]

1 nitpick

[maks-rafalko]

Thank you @BackEndTea