v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/model/terms_of_service.go

@@ -0,0 +1,54 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"fmt"
+	"net/http"
+	"unicode/utf8"
+)
+
+type TermsOfService struct {
+	Id       string `json:"id"`
+	CreateAt int64  `json:"create_at"`
+	UserId   string `json:"user_id"`
+	Text     string `json:"text"`
+}
+
+func (t *TermsOfService) IsValid() *AppError {
+	if !IsValidId(t.Id) {
+		return InvalidTermsOfServiceError("id", "")
+	}
+
+	if t.CreateAt == 0 {
+		return InvalidTermsOfServiceError("create_at", t.Id)
+	}
+
+	if !IsValidId(t.UserId) {
+		return InvalidTermsOfServiceError("user_id", t.Id)
+	}
+
+	if utf8.RuneCountInString(t.Text) > PostMessageMaxRunesV2 {
+		return InvalidTermsOfServiceError("text", t.Id)
+	}
+
+	return nil
+}
+
+func InvalidTermsOfServiceError(fieldName string, termsOfServiceId string) *AppError {
+	id := fmt.Sprintf("model.terms_of_service.is_valid.%s.app_error", fieldName)
+	details := ""
+	if termsOfServiceId != "" {
+		details = "terms_of_service_id=" + termsOfServiceId
+	}
+	return NewAppError("TermsOfService.IsValid", id, map[string]any{"MaxLength": PostMessageMaxRunesV2}, details, http.StatusBadRequest)
+}
+
+func (t *TermsOfService) PreSave() {
+	if t.Id == "" {
+		t.Id = NewId()
+	}
+
+	t.CreateAt = GetMillis()
+}