API: Allow Merge request filtering based on "updated_at" property

Description

The merge request api does not allow filtering based on last update time updated_at when listing MR.

Proposal

Add query parameter updated_after and updated_before for listing MR.

Links / references

https://docs.gitlab.com/ee/api/merge_requests.html#list-merge-requests

Documentation blurb

Overview & Use Cases

This feature will allow applications using Gitlab API to perform actions based on the updated_at property. This will provide a fine-grained control over the list of MRs.

Useful for: GitLab OAuth Applications.

Feature Checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.

• Feature assurance
• Documentation
• Added to features.yml

~"feature proposal" api