[FEATURE] Method to detect Form class name from convention

Placing a subclass of \FluidTYPO3\Flux\Form in `EXT:myext/Classes/Form/$controllerName/{$actionNameUcfirst}Form` loads that class and uses it as Flux form instead of loading form template.

`$controllerName` and `$actionNameUcfirst` are fetched from a record using the Provider class - new methods added to ProviderInterface to allow overriding the return values of these methods.