Deprecated Implicitly nullable from PHP 8.4

[sharpchi]

Just running code checking prepping for M4.5 and PHP 8.3 and noticed a warning about implict nulls in params.

#56: ····public·static·function·set_page_fake_url(moodle_url·$url·=·null)·{
Implicitly marking a parameter as nullable is deprecated since PHP 8.4. Update the type to be explicitly nullable instead. Found implicitly nullable parameter: $url. (PHPCompatibility.FunctionDeclarations.RemovedImplicitlyNullableParam.Deprecated)
#74: ····public·static·function·set_page_real_url(moodle_url·$url·=·null)·{
Implicitly marking a parameter as nullable is deprecated since PHP 8.4. Update the type to be explicitly nullable instead. Found implicitly nullable parameter: $url. (PHPCompatibility.FunctionDeclarations.RemovedImplicitlyNullableParam.Deprecated)

These can easily be remedied without breaking backward support: https://php.watch/versions/8.4/implicitly-marking-parameter-type-nullable-deprecated