[BE] Notification Channels : Pagination

User story:

• As a PMM Admin user, I need to be able to use pagination on the notification channels page so that I'll be able to configure a more suitable way of presenting data for me

UI/UX:

• See Figma

Acceptance criteria

• The user is able to see the Pagination element and use it
• the default value is 25 items per page
• the values in the "per page" selector: 25-50-100 (as in QAN)

Out of scope:

• persist pagination settings across browsers for the user

Suggested implementation:

TBD

Details:

TBD