Closes#14716Closes#14717
Adds a new user-scoped tailnet API endpoint (`api/v2/tailnet`) with a new RPC stream for receiving updates on workspaces owned by a specific user, as defined in #14716.
When a stream is started, the `WorkspaceUpdatesProvider` will begin listening on the user-scoped pubsub events implemented in #14964. When a relevant event type is seen (such as a workspace state transition), the provider will query the DB for all the workspaces (and agents) owned by the user. This gets compared against the result of the previous query to produce a set of workspace updates.
Workspace updates can be requested for any user ID, however only workspaces the authorised user is permitted to `ActionRead` will have their updates streamed.
Opening a tunnel to an agent requires that the user can perform `ActionSSH` against the workspace containing it.
This adds the ability for `TunnelAuth` to also authorize incoming wireguard node IPs, preventing agents from reporting anything other than their static IP generated from the agent ID.
