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/draft_test.go

@@ -0,0 +1,67 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDraftIsValid(t *testing.T) {
+	o := Draft{}
+	maxDraftSize := 10000
+
+	err := o.IsValid(maxDraftSize)
+	assert.NotNil(t, err)
+
+	o.CreateAt = GetMillis()
+	err = o.IsValid(maxDraftSize)
+	assert.NotNil(t, err)
+
+	o.UpdateAt = GetMillis()
+	err = o.IsValid(maxDraftSize)
+	assert.NotNil(t, err)
+
+	o.UserId = NewId()
+	err = o.IsValid(maxDraftSize)
+	assert.NotNil(t, err)
+
+	o.ChannelId = NewId()
+	o.RootId = "123"
+	err = o.IsValid(maxDraftSize)
+	assert.NotNil(t, err)
+
+	o.RootId = ""
+
+	o.Message = strings.Repeat("0", maxDraftSize+1)
+	err = o.IsValid(maxDraftSize)
+	assert.NotNil(t, err)
+
+	o.Message = strings.Repeat("0", maxDraftSize)
+	err = o.IsValid(maxDraftSize)
+	assert.Nil(t, err)
+
+	o.Message = "test"
+	err = o.IsValid(maxDraftSize)
+	assert.Nil(t, err)
+
+	o.FileIds = StringArray{strings.Repeat("0", maxDraftSize+1)}
+	err = o.IsValid(maxDraftSize)
+	assert.NotNil(t, err)
+}
+
+func TestDraftPreSave(t *testing.T) {
+	o := Draft{Message: "test"}
+	o.PreSave()
+
+	assert.NotEqual(t, 0, o.CreateAt)
+
+	past := GetMillis() - 1
+	o = Draft{Message: "test", CreateAt: past}
+	o.PreSave()
+
+	assert.LessOrEqual(t, o.CreateAt, past)
+}