Expose public/ API as submodule (#23345)

* model -> public/model

* plugin -> public/plugin

* public/model/utils -> public/utils

* platform/shared/mlog -> public/shared/mlog

* platform/shared/i18n -> public/shared/i18n

* platform/shared/markdown -> public/shared/markdown

* platform/services/timezones -> public/shared/timezones

* channels/einterfaces -> einterfaces

* expose public/ submodule

* go mod tidy

* .github: cache-dependency-path, setup-go-work

* modules-tidy for public/ too

* remove old gomodtidy

server/public/plugin/stringifier.go

@@ -0,0 +1,31 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package plugin
+
+import (
+	"fmt"
+)
+
+func stringify(objects []any) []string {
+	stringified := make([]string, len(objects))
+	for i, object := range objects {
+		stringified[i] = fmt.Sprintf("%+v", object)
+	}
+	return stringified
+}
+
+func toObjects(strings []string) []any {
+	if strings == nil {
+		return nil
+	}
+	objects := make([]any, len(strings))
+	for i, string := range strings {
+		objects[i] = string
+	}
+	return objects
+}
+
+func stringifyToObjects(objects []any) []any {
+	return toObjects(stringify(objects))
+}