Show toggle and tooltips for free namespace limit

What does this MR do and why?

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/352638

• This shows the toggle to indicate the current state of a membership of a user (being either active or awaiting).
• It disables the the toggle to activate members if the namespace already reached the limit
• It shows the correct amount of users that are billable for free namespaces (using the seats given from the API)

What this MR does not do

• It does not implement the functionality of the toggle (still dependent on the API)
• Fetching membership data from awaiting members fails because we exclude awaiting members in the API right now, this will be done in a separate backend MR (!86432 (merged))

No changelog as it's behind a feature flag free_user_cap

Screenshots or screen recordings

Free Namespace with Limit (this change)	Free namespace without Limit	Namespace on Subscription

How to set up and validate locally

export GITLAB_SIMULATE_SAAS=1
gdk start

You want to have three different groups

1. A free group

2. A free group where the Feature flag is enabled

   bin/rails c
   group = Group.find(1) # Use the ID of the group you want to test
   Feature.enable(:free_user_cap, group)

3. A group on a plan (go to http://localhost:3000/admin/groups, choose a group and set a plan). To be able to do this, you need to enable namespace plans:

   bin/rails c
   ApplicationSetting.first.update(check_namespace_plan: true) 

4. For each group, go to the Usage Quota Page: http://localhost:3000/groups/GROUP_NAME/-/usage_quotas#seats-quota-tab

How to activate/deactivate a user

group.members.last.wait # deactivates user
group.members.last.activate

Numbered steps to set up and validate the change are strongly suggested.

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.