MM-18517: Plugin Marketplace (Phase 2) (#13086)

* MM-17549: use StatusNotFound when deleting plugin (#12983)

Trying to delete a plugin that does not exist should fail with a 404, not a 400.

Relates-to: https://mattermost.atlassian.net/browse/MM-17549

* MM-19630: marketplace: model ReleaseNotesURL (#13083)

Automatic Merge

* MM-20065: allow prepackaged plugin upgrade (#13076)

* MM-20065: allow prepackaged plugin upgrade

When locally installing prepackaged plugins, skip if a plugin exists with the same id and is the same or a newer version.

This is effectively a "poor man's" rework of prepackaged plugins to allow upgrade of prepackaged plugins via the marketplace. The larger plan to rework prepackaged plugins was deferred from v5.18.

Fixes: https://mattermost.atlassian.net/browse/MM-20065

* eliminate unnecessary installPlugin

* fix TestPluginSync defaults to match minio

* cleanExistingBundles

* close prepackaged filereader

* simplify

api4/plugin_test.go

@@ -206,7 +206,7 @@ func TestPlugin(t *testing.T) {
 
 	// Deactivate error case
 	ok, resp = th.SystemAdminClient.DisablePlugin("junk")
-	CheckBadRequestStatus(t, resp)
+	CheckNotFoundStatus(t, resp)
 	assert.False(t, ok)
 
 	// Get error cases
@@ -241,7 +241,7 @@ func TestPlugin(t *testing.T) {
 
 	// Remove error cases
 	ok, resp = th.SystemAdminClient.RemovePlugin(manifest.Id)
-	CheckBadRequestStatus(t, resp)
+	CheckNotFoundStatus(t, resp)
 	assert.False(t, ok)
 
 	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.PluginSettings.Enable = false })
@@ -253,7 +253,7 @@ func TestPlugin(t *testing.T) {
 	CheckForbiddenStatus(t, resp)
 
 	_, resp = th.SystemAdminClient.RemovePlugin("bad.id")
-	CheckBadRequestStatus(t, resp)
+	CheckNotFoundStatus(t, resp)
 }
 
 func TestNotifyClusterPluginEvent(t *testing.T) {