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

app/server.go

@@ -24,6 +24,7 @@ import (
 	"github.com/throttled/throttled"
 	"golang.org/x/crypto/acme/autocert"
 
+	"github.com/mattermost/mattermost-server/config"
 	"github.com/mattermost/mattermost-server/einterfaces"
 	"github.com/mattermost/mattermost-server/jobs"
 	"github.com/mattermost/mattermost-server/mlog"
@@ -96,7 +97,7 @@ type Server struct {
 	logListenerId           string
 	clusterLeaderListenerId string
 	disableConfigWatch      bool
-	configWatcher           *utils.ConfigWatcher
+	configWatcher           *config.ConfigWatcher
 	asymmetricSigningKey    *ecdsa.PrivateKey
 
 	pluginCommands     []*PluginCommand
@@ -144,7 +145,9 @@ func NewServer(options ...Option) (*Server, error) {
 		clientConfig:            make(map[string]string),
 	}
 	for _, option := range options {
-		option(s)
+		if err := option(s); err != nil {
+			return nil, errors.Wrap(err, "failed to apply option")
+		}
 	}
 
 	if err := s.LoadConfig(s.configFile); err != nil {