[SIMD] make Mask an alias to Rebind<bool, ...>

See !609 (comment 53119)

mentioned in merge request !609 (merged)

mentioned in commit 2fbeef50

mentioned in merge request !612 (merged)

mentioned in commit cd6c050d

mentioned in issue extensions/dune-vectorclass#8 (closed)

TODO:

• extensions/dune-vectorclass#8 (closed)
• Remove deprecation and declaration of Overloads::MaskType again (!615 (merged))

mentioned in commit b706dd86

mentioned in merge request !615 (merged)

closed via merge request !615 (merged)

mentioned in commit 144ec481