Adding EnsureBot plugin helper. (#10542)

* Adding EnsureBot plugin helper.

* Removing unessisary GetBot call.

* Moving to own file and error handling cleanup.

* Removing patch functionaliy. Plugins should manage their own bot account updates for now.

* Adding tests and cleaning up errors.

* Modify to not shadow err.

* Moving helpers to seperate interface.

* Feedback fixes

plugin/client.go

@@ -7,16 +7,21 @@ import (
 	"github.com/hashicorp/go-plugin"
 )
 
+const (
+	INTERNAL_KEY_PREFIX = "mmi_"
+	BOT_USER_KEY        = INTERNAL_KEY_PREFIX + "botid"
+)
+
 // Starts the serving of a Mattermost plugin over net/rpc. gRPC is not yet supported.
 //
 // Call this when your plugin is ready to start.
 func ClientMain(pluginImplementation interface{}) {
 	if impl, ok := pluginImplementation.(interface {
-		SetAPI(api API)
+		SetAPI(api API, helpers Helpers)
 	}); !ok {
 		panic("Plugin implementation given must embed plugin.MattermostPlugin")
 	} else {
-		impl.SetAPI(nil)
+		impl.SetAPI(nil, nil)
 	}
 
 	pluginMap := map[string]plugin.Plugin{
@@ -31,11 +36,13 @@ func ClientMain(pluginImplementation interface{}) {
 
 type MattermostPlugin struct {
 	// API exposes the plugin api, and becomes available just prior to the OnActive hook.
-	API API
+	API     API
+	Helpers Helpers
 }
 
 // SetAPI persists the given API interface to the plugin. It is invoked just prior to the
 // OnActivate hook, exposing the API for use by the plugin.
-func (p *MattermostPlugin) SetAPI(api API) {
+func (p *MattermostPlugin) SetAPI(api API, helpers Helpers) {
 	p.API = api
+	p.Helpers = helpers
 }