Add updated_before and updated_after filters to iterations API

What does this MR do and why?

REST API now allows filtering results by the date they were last updated at

How to set up and validate locally

curl --header "PRIVATE-TOKEN: <token>" "http://localhost:3000/api/v4/projects/6/iterations?updated_before=2014-02-17T09%3A24%3A18Z"

curl --header "PRIVATE-TOKEN: <token>" "http://localhost:3000/api/v4/projects/6/iterations?updated_after=2023-02-14T09%3A24%3A18Z"

curl --header "PRIVATE-TOKEN: <token>" "http://localhost:3000/api/v4/groups/6/iterations?updated_before=2023-02-14T09%3A24%3A18Z"

curl --header "PRIVATE-TOKEN: <token>" "http://localhost:3000/api/v4/groups/6/iterations?updated_after=2023-02-14T09%3A24%3A18Z"

Database review

Both project and group level requests will generate the same group level query. Project level requests will simply get iterations from the parent group the project belongs to.

Group level updated before

https://console.postgres.ai/shared/fb454d3e-f3d0-4ed5-a692-0354abcd769e

```sql SELECT "sprints".* FROM "sprints" WHERE "sprints"."group_id" IN ( SELECT "namespaces"."id" FROM "namespaces" WHERE "namespaces"."type" = 'Group' AND "namespaces"."id" = 9970 ) AND "sprints"."updated_at" <= '2022-12-17 09:24:18' ORDER BY "sprints"."due_date" ASC, "sprints"."title" ASC, "sprints"."id" ASC LIMIT 20 OFFSET 0 ```

Group level updated after

https://console.postgres.ai/shared/2e0b106e-811e-418d-8a2c-22668df048a7

```sql SELECT "sprints".* FROM "sprints" WHERE "sprints"."group_id" IN ( SELECT "namespaces"."id" FROM "namespaces" WHERE "namespaces"."type" = 'Group' AND "namespaces"."id" = 9970 ) AND "sprints"."updated_at" >= '2022-12-17 09:24:18' ORDER BY "sprints"."due_date" ASC, "sprints"."title" ASC, "sprints"."id" ASC LIMIT 20 OFFSET 0 ```

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #378662 (closed)