move storage maps to blake2_128 (#2268)

* remove default hash, introduce twox_128 and blake2

* use blake2_128 & create ext_blake2_128

* refactor code

* add benchmark

* factorize generator

* fix

* parameterizable hasher

* some fix

* fix

* fix

* fix

* metadata

* fix

* remove debug print

* map -> blake2_256

* fix test

* fix test

* Apply suggestions from code review

Co-Authored-By: thiolliere <[email protected]>

* impl twox 128 concat (#2353)

* impl twox_128_concat

* comment addressed

* fix

* impl twox_128->64_concat

* fix test