feat(indexes): support all Postgresql index types

[pierresouchay]

Context: We can have other index types than hash, btree

Solution: Implement all of them for Postsgreql as described in https://www.postgresql.org/docs/current/indexes-types.html

Note that SP-GiST is named spgistin indexes of Postgresql, (similar to B-Tree -> btree)

Ref: #56