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/model/github_release.go

@@ -0,0 +1,26 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"net/http"
+)
+
+type GithubReleaseInfo struct {
+	Id          int    `json:"id"`
+	TagName     string `json:"tag_name"`
+	Name        string `json:"name"`
+	CreatedAt   string `json:"created_at"`
+	PublishedAt string `json:"published_at"`
+	Body        string `json:"body"`
+	Url         string `json:"html_url"`
+}
+
+func (g *GithubReleaseInfo) IsValid() *AppError {
+	if g.Id == 0 {
+		return NewAppError("GithubReleaseInfo.IsValid", NoTranslation, nil, "empty ID", http.StatusInternalServerError)
+	}
+
+	return nil
+}