[10.x] Remove redundant 'setAccessible' methods

[bradietilley]

The setAccessible() method has had no effect (i.e. is redundant) as of PHP 8.1

Laravel 10 has a minimum requirement of PHP 8.1, therefore officially dropping the requirement to retain these methods.

This PR simply removes all instances of ->setAccessible(true) from all ReflectionProperty and ReflectionMethod objects throughout the src/ and tests/ directories.

Sources:

ReflectionMethod::setAccessible(): https://www.php.net/manual/en/reflectionmethod.setaccessible.php

Note: As of PHP 8.1.0, calling this method has no effect; all methods are invokable by default.

ReflectionProperty::setAccessible(): https://www.php.net/manual/en/reflectionproperty.setaccessible.php

Note: As of PHP 8.1.0, calling this method has no effect; all properties are accessible by default.