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/member_invite.go

@@ -0,0 +1,56 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+type MemberInvite struct {
+	Emails     []string `json:"emails"`
+	ChannelIds []string `json:"channelIds,omitempty"`
+	Message    string   `json:"message"`
+}
+
+func (i *MemberInvite) Auditable() map[string]interface{} {
+	return map[string]interface{}{
+		"emails":      i.Emails,
+		"channel_ids": i.ChannelIds,
+	}
+}
+
+// IsValid validates that the invitation info is loaded correctly and with the correct structure
+func (i *MemberInvite) IsValid() *AppError {
+	if len(i.Emails) == 0 {
+		return NewAppError("MemberInvite.IsValid", "model.member.is_valid.emails.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if len(i.ChannelIds) > 0 {
+		for _, channel := range i.ChannelIds {
+			if len(channel) != 26 {
+				return NewAppError("MemberInvite.IsValid", "model.member.is_valid.channel.app_error", nil, "channel="+channel, http.StatusBadRequest)
+			}
+		}
+	}
+
+	return nil
+}
+
+func (i *MemberInvite) UnmarshalJSON(b []byte) error {
+	var emails []string
+	if err := json.Unmarshal(b, &emails); err == nil {
+		*i = MemberInvite{}
+		i.Emails = emails
+		return nil
+	}
+
+	type TempMemberInvite MemberInvite
+	var o2 TempMemberInvite
+	if err := json.Unmarshal(b, &o2); err != nil {
+		return err
+	}
+	*i = MemberInvite(o2)
+	return nil
+}