MM-13893: refactor config (#10230)

* refactor utils/config* to config/

* pull validateLdapFilter into app

* clean up Config/GetConfig/GetSanitizedConfig usage

Eliminate app.GetConfig() in favour of just using app.Config() directly,
but expose app.GetSanitizedConfig() for when the old behaviour was
required.

* web: isolate config setup

* TestInvitePeopleProvider: make config explicit

* regenerateClientConfig: avoid racey map access

* integrate watch flag into app.ConfigFile option

* make app.Option return an error

* release.mk: only cp static files from config/

* release.mk: fix cp static files from config/

* api4: TestPlugin cleanup

* s/c/cfg/ for clarity

* fix merge conflict

* testlib: allow customization of testlib driver name

api4/system_test.go

@@ -131,19 +131,19 @@ func TestUpdateConfig(t *testing.T) {
 	require.Equal(t, SiteName, cfg.TeamSettings.SiteName, "It should update the SiteName")
 
 	t.Run("Should not be able to modify PluginSettings.EnableUploads", func(t *testing.T) {
-		oldEnableUploads := *th.App.GetConfig().PluginSettings.EnableUploads
+		oldEnableUploads := *th.App.Config().PluginSettings.EnableUploads
 		*cfg.PluginSettings.EnableUploads = !oldEnableUploads
 
 		cfg, resp = th.SystemAdminClient.UpdateConfig(cfg)
 		CheckNoError(t, resp)
 		assert.Equal(t, oldEnableUploads, *cfg.PluginSettings.EnableUploads)
-		assert.Equal(t, oldEnableUploads, *th.App.GetConfig().PluginSettings.EnableUploads)
+		assert.Equal(t, oldEnableUploads, *th.App.Config().PluginSettings.EnableUploads)
 
 		cfg.PluginSettings.EnableUploads = nil
 		cfg, resp = th.SystemAdminClient.UpdateConfig(cfg)
 		CheckNoError(t, resp)
 		assert.Equal(t, oldEnableUploads, *cfg.PluginSettings.EnableUploads)
-		assert.Equal(t, oldEnableUploads, *th.App.GetConfig().PluginSettings.EnableUploads)
+		assert.Equal(t, oldEnableUploads, *th.App.Config().PluginSettings.EnableUploads)
 	})
 }