Plugin framework: add ability to install other plugins to the… (#12232)

* add ability to upload other plugins to the plugin API

* generated client rpc glue code

* fix UploadPlugin API signature

* generated plugin mocks

* added upload plugin test

* removed unused comment

* using single line to call InstallPlugin with file Reader

* fix minimum server version

* added successful plugin upload test

* renamed UploadPlugin to InstallPlugin

plugin/plugintest/api.go

@@ -5,6 +5,8 @@
 package plugintest
 
 import (
+	io "io"
+
 	model "github.com/mattermost/mattermost-server/model"
 	mock "github.com/stretchr/testify/mock"
 )
@@ -2783,3 +2785,28 @@ func (_m *API) UploadFile(data []byte, channelId string, filename string) (*mode
 
 	return r0, r1
 }
+
+// InstallPlugin provides a mock function with given fields: file, replace
+func (_m *API) InstallPlugin(file io.Reader, replace bool) (*model.Manifest, *model.AppError) {
+	ret := _m.Called(file, replace)
+
+	var r0 *model.Manifest
+	if rf, ok := ret.Get(0).(func(io.Reader, bool) *model.Manifest); ok {
+		r0 = rf(file, replace)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).(*model.Manifest)
+		}
+	}
+
+	var r1 *model.AppError
+	if rf, ok := ret.Get(1).(func(io.Reader, bool) *model.AppError); ok {
+		r1 = rf(file, replace)
+	} else {
+		if ret.Get(1) != nil {
+			r1 = ret.Get(1).(*model.AppError)
+		}
+	}
+
+	return r0, r1
+}