Add entity support for graphql rate-limiting cost decorators in deck

[Prashansa-K]

We need to add crud support for graphql rate-limiting cost decorators in deck.
Entity: https://github.com/Kong/go-kong/blob/main/kong/graphql_rate_limiting.go

This is a custom entity. Deck already supports one such entity i.e. degraphql_routes.
We need to follow the same format for this new entity - custom entity parsers are already present.

Slack convo: https://kongstrong.slack.com/archives/C07AQH7SAF8/p1772429574371399

[shivaygupta-dotcom]

Dev and most of the testing is done from my end but there are two issues on Put(KGW) and Delete(Konnect) which are blocker for this for final testing.
KGW: https://kongstrong.slack.com/archives/C03CTMSHP6C/p1773819433228709
Konnect: https://kongstrong.slack.com/archives/C07AQH7SAF8/p1773995542061319?thread_ts=1772429574.371399&cid=C07AQH7SAF8