Add more usage data to EE ping

This MR loads the EE usage ping asynchronously on the admin application settings page and now includes the counts of the following items:

* Comments
* Groups
* Users
* Projects
* Issues
* Labels
* CI builds
* Snippets
* Milestones
* Todos
* Pushes
* Merge requests
* Environments
* Triggers
* Deploy keys
* Pages
* Project Services
* Issue Boards
* CI Runners
* Deployments
* Geo Nodes
* LDAP Groups
* LDAP Keys
* LDAP Users
* LFS objects
* Protected branches
* Releases
* Remote mirrors
* Web hooks

Closes #997

See merge request !735