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/draft.go

@@ -0,0 +1,104 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"net/http"
+	"sync"
+	"unicode/utf8"
+)
+
+type Draft struct {
+	CreateAt  int64  `json:"create_at"`
+	UpdateAt  int64  `json:"update_at"`
+	DeleteAt  int64  `json:"delete_at"`
+	UserId    string `json:"user_id"`
+	ChannelId string `json:"channel_id"`
+	RootId    string `json:"root_id"`
+
+	Message string `json:"message"`
+
+	propsMu  sync.RWMutex    `db:"-"`       // Unexported mutex used to guard Draft.Props.
+	Props    StringInterface `json:"props"` // Deprecated: use GetProps()
+	FileIds  StringArray     `json:"file_ids,omitempty"`
+	Metadata *PostMetadata   `json:"metadata,omitempty"`
+	Priority StringInterface `json:"priority,omitempty"`
+}
+
+func (o *Draft) IsValid(maxDraftSize int) *AppError {
+	if o.CreateAt == 0 {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.create_at.app_error", nil, "channelid="+o.ChannelId, http.StatusBadRequest)
+	}
+
+	if o.UpdateAt == 0 {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.update_at.app_error", nil, "channelid="+o.ChannelId, http.StatusBadRequest)
+	}
+
+	if !IsValidId(o.UserId) {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.user_id.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if !IsValidId(o.ChannelId) {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.channel_id.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if !(IsValidId(o.RootId) || o.RootId == "") {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.root_id.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if utf8.RuneCountInString(o.Message) > maxDraftSize {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.msg.app_error", nil, "channelid="+o.ChannelId, http.StatusBadRequest)
+	}
+
+	if utf8.RuneCountInString(ArrayToJSON(o.FileIds)) > PostFileidsMaxRunes {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.file_ids.app_error", nil, "channelid="+o.ChannelId, http.StatusBadRequest)
+	}
+
+	if utf8.RuneCountInString(StringInterfaceToJSON(o.GetProps())) > PostPropsMaxRunes {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.props.app_error", nil, "channelid="+o.ChannelId, http.StatusBadRequest)
+	}
+
+	if utf8.RuneCountInString(StringInterfaceToJSON(o.Priority)) > PostPropsMaxRunes {
+		return NewAppError("Drafts.IsValid", "model.draft.is_valid.priority.app_error", nil, "channelid="+o.ChannelId, http.StatusBadRequest)
+	}
+
+	return nil
+}
+
+func (o *Draft) SetProps(props StringInterface) {
+	o.propsMu.Lock()
+	defer o.propsMu.Unlock()
+	o.Props = props
+}
+
+func (o *Draft) GetProps() StringInterface {
+	o.propsMu.RLock()
+	defer o.propsMu.RUnlock()
+	return o.Props
+}
+
+func (o *Draft) PreSave() {
+	if o.CreateAt == 0 {
+		o.CreateAt = GetMillis()
+		o.UpdateAt = o.CreateAt
+	} else {
+		o.UpdateAt = GetMillis()
+	}
+
+	o.DeleteAt = 0
+	o.PreCommit()
+}
+
+func (o *Draft) PreCommit() {
+	if o.GetProps() == nil {
+		o.SetProps(make(map[string]interface{}))
+	}
+
+	if o.FileIds == nil {
+		o.FileIds = []string{}
+	}
+
+	// There's a rare bug where the client sends up duplicate FileIds so protect against that
+	o.FileIds = RemoveDuplicateStrings(o.FileIds)
+}