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/token.go

@@ -0,0 +1,42 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"net/http"
+)
+
+const (
+	TokenSize          = 64
+	MaxTokenExipryTime = 1000 * 60 * 60 * 48 // 48 hour
+	TokenTypeOAuth     = "oauth"
+)
+
+type Token struct {
+	Token    string
+	CreateAt int64
+	Type     string
+	Extra    string
+}
+
+func NewToken(tokentype, extra string) *Token {
+	return &Token{
+		Token:    NewRandomString(TokenSize),
+		CreateAt: GetMillis(),
+		Type:     tokentype,
+		Extra:    extra,
+	}
+}
+
+func (t *Token) IsValid() *AppError {
+	if len(t.Token) != TokenSize {
+		return NewAppError("Token.IsValid", "model.token.is_valid.size", nil, "", http.StatusInternalServerError)
+	}
+
+	if t.CreateAt == 0 {
+		return NewAppError("Token.IsValid", "model.token.is_valid.expiry", nil, "", http.StatusInternalServerError)
+	}
+
+	return nil
+}