Mask types dont need additional parameters.

[edanor]

Mask types use additional parameter for scalar type. The original reason for that was to be able to specialize mask types for different scalar types, but this is unnecessary for AVX512 and other extensions already use only one mask representative.

This is unnecessary and should be removed across all plugins.

[edanor]

Mask types now use only VEC_LEN as a template parameter. Any other dependant type can be handled using mask traits.