Fetch and render exclusion list

What does this MR do and why?

It fetches and renders storage enforcement exclusion list in the exclusion table.

Note: this MR depends on !116248 (merged) to be merged first.

Screenshots or screen recordings

Screencast	Before	After
Screen_Recording_2023-05-29_at_12.28.47

How to set up and validate locally

• In bin/rails console run:

    Feature.enable(:namespace_limits_admin_dashboard)
    ::Gitlab::CurrentSettings.update(check_namespace_plan: true)

• Simulate saas and restart your gdk

  $ export GITLAB_SIMULATE_SAAS=1
  $ gdk restart

• Visit /admin/namespace_limits as root

• In the form at the end of the page, select a namespace and type a reason for exclusion then submit

• Observe the table being refreshed

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 #381682