[v16] Machine ID: Bot instance management in tctl bots instances (#…

…47225)

* Machine ID: Bot instance management in `tctl bots instances`

This adds new new subcommands to `tctl` to manage bot instances:
- `tctl bots instances list` lists bot instances
- `tctl bots instances show` shows a specific bot instance
- `tctl bots instances add` adds a new instance to an existing bot

This also adds help text to guide users between the new commands. It
also adds a few aliases for common alternate command names.

* Fix lints

* Apply suggestions from code review

Co-authored-by: Zac Bergquist <[email protected]>

* Add note on other join methods, fix other review comments

* Fix import ordering

---------

Co-authored-by: Zac Bergquist <[email protected]>

tool/tctl/common/admin_action_test.go

@@ -174,6 +174,12 @@ func (s *adminActionTestSuite) testBots(t *testing.T) {
 				setup:      createBot,
 				cleanup:    deleteBot,
 			},
+			"tctl bots instance add": {
+				command:    fmt.Sprintf("bots instance add %v", botName),
+				cliCommand: &tctl.BotsCommand{},
+				setup:      createBot,
+				cleanup:    deleteBot,
+			},
 		} {
 			t.Run(name, func(t *testing.T) {
 				s.testCommand(t, ctx, tc)