Respect index option param.

[abbyssoul]

• [X ] Do only one thing
• [ X] Non breaking API changes
• [ X] Tested

What did this pull request do?

When creating indexes, the option argument is taken into account.

User Case Description

When creating indexes, users might need greater control over the resulting DDL statement. For example, users need a way to specify "NULLS [ NOT ] DISTINCT" SQL option when working with Postgres as described here: https://www.postgresql.org/docs/current/sql-createindex.html
Despite documentation stating that option param is supported: https://gorm.io/docs/indexes.html, Postgres Mirgator implementation does not use it. Example of use opened issue that will be closed by this PR: go-gorm/gorm#6085

[abbyssoul]

Hi @a631807682 ,
Thank you for approving this PR.
Unfortunately, I don't have write access to this repo. Would you or someone else with permissions, be able to merge it in plz.