MM-44953: Refactor EnsureBot to be used from plugin.API (#20521)

The mattermost-plugin-api code also needs to use this.
Hence we make it available from plugin.API.

https://mattermost.atlassian.net/browse/MM-44953

```release-note
NONE
```

plugin/api.go

@@ -1152,6 +1152,11 @@ type API interface {
 	//
 	// Minimum server version: 7.0
 	GetCloudLimits() (*model.ProductLimits, error)
+
+	// EnsureBotUser updates the bot if it exists, otherwise creates it.
+	//
+	// Minimum server version: 7.1
+	EnsureBotUser(bot *model.Bot) (string, error)
 }
 
 var handshake = plugin.HandshakeConfig{

plugin/api_timer_layer_generated.go

@@ -1232,3 +1232,10 @@ func (api *apiTimerLayer) GetCloudLimits() (*model.ProductLimits, error) {
 	api.recordTime(startTime, "GetCloudLimits", _returnsB == nil)
 	return _returnsA, _returnsB
 }
+
+func (api *apiTimerLayer) EnsureBotUser(bot *model.Bot) (string, error) {
+	startTime := timePkg.Now()
+	_returnsA, _returnsB := api.apiImpl.EnsureBotUser(bot)
+	api.recordTime(startTime, "EnsureBotUser", _returnsB == nil)
+	return _returnsA, _returnsB
+}

plugin/client_rpc_generated.go

@@ -5678,3 +5678,33 @@ func (s *apiRPCServer) GetCloudLimits(args *Z_GetCloudLimitsArgs, returns *Z_Get
 	}
 	return nil
 }
+
+type Z_EnsureBotUserArgs struct {
+	A *model.Bot
+}
+
+type Z_EnsureBotUserReturns struct {
+	A string
+	B error
+}
+
+func (g *apiRPCClient) EnsureBotUser(bot *model.Bot) (string, error) {
+	_args := &Z_EnsureBotUserArgs{bot}
+	_returns := &Z_EnsureBotUserReturns{}
+	if err := g.client.Call("Plugin.EnsureBotUser", _args, _returns); err != nil {
+		log.Printf("RPC call to EnsureBotUser API failed: %s", err.Error())
+	}
+	return _returns.A, _returns.B
+}
+
+func (s *apiRPCServer) EnsureBotUser(args *Z_EnsureBotUserArgs, returns *Z_EnsureBotUserReturns) error {
+	if hook, ok := s.impl.(interface {
+		EnsureBotUser(bot *model.Bot) (string, error)
+	}); ok {
+		returns.A, returns.B = hook.EnsureBotUser(args.A)
+		returns.B = encodableError(returns.B)
+	} else {
+		return encodableError(fmt.Errorf("API EnsureBotUser called but not implemented."))
+	}
+	return nil
+}

plugin/plugintest/api.go

@@ -620,6 +620,27 @@ func (_m *API) EnablePlugin(id string) *model.AppError {
 	return r0
 }
 
+// EnsureBotUser provides a mock function with given fields: bot
+func (_m *API) EnsureBotUser(bot *model.Bot) (string, error) {
+	ret := _m.Called(bot)
+
+	var r0 string
+	if rf, ok := ret.Get(0).(func(*model.Bot) string); ok {
+		r0 = rf(bot)
+	} else {
+		r0 = ret.Get(0).(string)
+	}
+
+	var r1 error
+	if rf, ok := ret.Get(1).(func(*model.Bot) error); ok {
+		r1 = rf(bot)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
 // ExecuteSlashCommand provides a mock function with given fields: commandArgs
 func (_m *API) ExecuteSlashCommand(commandArgs *model.CommandArgs) (*model.CommandResponse, error) {
 	ret := _m.Called(commandArgs)