Convert HostsPage and HostsTable to typescript
Display page-spinner if hostpage in loading state
Add error state to HostsPage
Fix tests for HostsPage
Update Changelog
Add missing type definitions to HostsTable
Update Source & SourceLinks types to be current with all fields.
Properly mocked hosts & env mock api fns for spying.
Add note about kapacitors field on Source type differing
between client and server.
Co-authored-by Iris Scholten <ischolten.is@gmail.com>