feat: added whomai cmd to coder cli (#13814)

* feat: added whomai cmd to coder cli
* refactor: update Coder CLI's whoami command to use client URL instead of deployment config
* feat(cli): add unit tests for the whoami command
* chore(docs): add coder command to fetch authenticated user info
* chore(doc): update help desc

cli/root.go

@@ -117,6 +117,7 @@ func (r *RootCmd) CoreSubcommands() []*serpent.Command {
 		r.stop(),
 		r.unfavorite(),
 		r.update(),
+		r.whoami(),
 
 		// Hidden
 		r.gitssh(),