Add a configuration to allow the user to set the Fluid namespaces
These namespaces should be the default for this new configuration:
f = TYPO3\CMS\Fluid\ViewHelpers // TYPO3
f = TYPO3Fluid\Fluid\ViewHelpers // FluidStandalone
f = TYPO3\Fluid\ViewHelpers // Neos
f = Neos\FluidAdaptor\ViewHelpers // FluidAdaptor for Neos