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/initial_load.go

@@ -0,0 +1,14 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+type InitialLoad struct {
+	User        *User             `json:"user"`
+	TeamMembers []*TeamMember     `json:"team_members"`
+	Teams       []*Team           `json:"teams"`
+	Preferences Preferences       `json:"preferences"`
+	ClientCfg   map[string]string `json:"client_cfg"`
+	LicenseCfg  map[string]string `json:"license_cfg"`
+	NoAccounts  bool              `json:"no_accounts"`
+}