Update GatewayResolver.php

[itashia]

###Use Class Constants:
Replace long conditionals with a simple and readable mapping

###Better type hints:
Add type hints for methods (especially getSupportedPorts)

Improved readability:

Use null instead of !is_null()
Use !== operator for strict comparison
Use $request->get() with default value

Separate logic:

Extract port detection logic into separate resolvePortName method
Improved security:
Added third parameter true to in_array for strict data type checking

Cleaner code:

Remove duplicate comments
Sort out use statements
Improved performance:
Reduce number of duplicate checks