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/reaction.go

@@ -0,0 +1,66 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"net/http"
+	"regexp"
+)
+
+type Reaction struct {
+	UserId    string  `json:"user_id"`
+	PostId    string  `json:"post_id"`
+	EmojiName string  `json:"emoji_name"`
+	CreateAt  int64   `json:"create_at"`
+	UpdateAt  int64   `json:"update_at"`
+	DeleteAt  int64   `json:"delete_at"`
+	RemoteId  *string `json:"remote_id"`
+	ChannelId string  `json:"channel_id"`
+}
+
+func (o *Reaction) IsValid() *AppError {
+	if !IsValidId(o.UserId) {
+		return NewAppError("Reaction.IsValid", "model.reaction.is_valid.user_id.app_error", nil, "user_id="+o.UserId, http.StatusBadRequest)
+	}
+
+	if !IsValidId(o.PostId) {
+		return NewAppError("Reaction.IsValid", "model.reaction.is_valid.post_id.app_error", nil, "post_id="+o.PostId, http.StatusBadRequest)
+	}
+
+	validName := regexp.MustCompile(`^[a-zA-Z0-9\-\+_]+$`)
+
+	if o.EmojiName == "" || len(o.EmojiName) > EmojiNameMaxLength || !validName.MatchString(o.EmojiName) {
+		return NewAppError("Reaction.IsValid", "model.reaction.is_valid.emoji_name.app_error", nil, "emoji_name="+o.EmojiName, http.StatusBadRequest)
+	}
+
+	if o.CreateAt == 0 {
+		return NewAppError("Reaction.IsValid", "model.reaction.is_valid.create_at.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if o.UpdateAt == 0 {
+		return NewAppError("Reaction.IsValid", "model.reaction.is_valid.update_at.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}
+
+func (o *Reaction) PreSave() {
+	if o.CreateAt == 0 {
+		o.CreateAt = GetMillis()
+	}
+	o.UpdateAt = GetMillis()
+	o.DeleteAt = 0
+
+	if o.RemoteId == nil {
+		o.RemoteId = NewString("")
+	}
+}
+
+func (o *Reaction) PreUpdate() {
+	o.UpdateAt = GetMillis()
+
+	if o.RemoteId == nil {
+		o.RemoteId = NewString("")
+	}
+}