[YSQL] Support GIN and GIST index methods

[robertpang]

Jira Link: DB-1851
YugaByte DB currently supports btree and hash index methods only. Consider supporting other index methods:

Index Method	Status	Comments
GIN	✅	Follow-ups tracked in #7850
GIST	⬜️	Tracked in #25825

[Aynn]

Aw, this is the one thing preventing me from committing to yugabyte

[danielisen]

Ran into the need for this trying to run promscale with YB (specifically the need for support for gin indexes).

[airhorns]

Just want to note another vote for this feature -- would be really amazing, especially when using JSONB fields to get a best-of-both-worlds SQL + NoSQL kind of system going.

[EmiPhil]

Please!

This and (at least) #997 (exclusion constraint) are required for doing temporal tables sanely. For example a table to track the valid state of a user job table where you want to constrain the user to only have one job_id at any given point in time:

create table temporal (
    user_id text,
    job_id text,
    valid_time tstzrange,
    exclude using gist (user_id with =, job_id with =, vaild_time with &&)
)

[samarpanB]

Very much in need of this please. How can we get a feature prioritized here ?

[sash2222]

it will be a cannon. Please prioritize the task! Please.