add config array for custom filter types

Signed-off-by:Eric Villard <dev@eviweb.fr>
refactor file type filter classes

Signed-off-by:Eric Villard <dev@eviweb.fr>
add a provider class for file type filters

Signed-off-by:Eric Villard <dev@eviweb.fr>
AssetFilters now uses FileTypeFilterProvider

Signed-off-by:Eric Villard <dev@eviweb.fr>