MM-16261 - Store Plugin in File Store (#11511)

* Implemneted saving the plugin bundle on the file store upon plugin upload

* Fixed compilation error

* Fixed compilation issue

* Added deletion from file store upon plugin uninstall

* Added condition to delete from store only when exists. Added case of saving the bundle to the store when uploading from url. Added checks in plugin tests

* Fixed compilation error

* Moved storage of plugin bundle within app/installPlugin

* Moved storing to filestore before enabling the plugin

* Fixed error handling

* Code styling improvements

* Minor styling fix

api4/plugin_test.go

@@ -57,6 +57,11 @@ func TestPlugin(t *testing.T) {
 	CheckNoError(t, resp)
 	assert.Equal(t, "testplugin", manifest.Id)
 
+	// Stored in File Store: Install Plugin from URL case
+	pluginStored, err := th.App.FileExists("./plugins/" + manifest.Id + ".tar.gz")
+	assert.Nil(t, err)
+	assert.True(t, pluginStored)
+
 	th.App.RemovePlugin(manifest.Id)
 
 	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.PluginSettings.Enable = false })
@@ -89,6 +94,11 @@ func TestPlugin(t *testing.T) {
 
 	assert.Equal(t, "testplugin", manifest.Id)
 
+	// Stored in File Store: Upload Plugin case
+	pluginStored, err = th.App.FileExists("./plugins/" + manifest.Id + ".tar.gz")
+	assert.Nil(t, err)
+	assert.True(t, pluginStored)
+
 	// Upload error cases
 	_, resp = th.SystemAdminClient.UploadPlugin(bytes.NewReader([]byte("badfile")))
 	CheckBadRequestStatus(t, resp)