Move two performance-oriented Rector rules into the shared rector set, so every rector package picks them up:

• NoScopeFetchBeforeCheapGuardRule - flags ScopeFetcher::fetch() called right before a cheap guard that does not use the scope; the guard should run first so most nodes bail out before scope resolution.
• NarrowReturnToUnionParamRule - flags a method that takes a class-type union param (A|B) but declares a broader single return type (e.g. their shared parent Node) and returns that very param; the return type should be the explicit union.

Both were living in rector-src/utils. They depend only on PhpParser/PHPStan plus Rector\PHPStan\ScopeFetcher, so they are reusable across all rector packages.

Registered in config/rector-rules.neon, tests under tests/Rules/Rector.