feat: support for case insensitive for contains and like queries

[nityanandagohain]

This PR adds case insensitive support to like/ilike/contains/ncontains

Attributes

• We are taking the tradeoff that contains/ncontains/like/ilike won't use the index.

Resources

• As of now we have two index for resources one is lowecase and the other one is uppercase.
• Since we want case insensitivity for like/ilike/contains/ncontains , we are using the lowercase index.

For body and resource we are making sure case insensitive search works by using like with lower(column).

For #5555

[nityanandagohain]

Have made a small change with respect to index filter to build it with lowercase which was missed, please have a look at the last commit.