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/audit.go

@@ -0,0 +1,14 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+type Audit struct {
+	Id        string `json:"id"`
+	CreateAt  int64  `json:"create_at"`
+	UserId    string `json:"user_id"`
+	Action    string `json:"action"`
+	ExtraInfo string `json:"extra_info"`
+	IpAddress string `json:"ip_address"`
+	SessionId string `json:"session_id"`
+}