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/emoji_test.go

@@ -0,0 +1,64 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestEmojiIsValid(t *testing.T) {
+	emoji := Emoji{
+		Id:        NewId(),
+		CreateAt:  1234,
+		UpdateAt:  1234,
+		DeleteAt:  0,
+		CreatorId: NewId(),
+		Name:      "name",
+	}
+
+	require.Nil(t, emoji.IsValid())
+
+	emoji.Id = "1234"
+	require.NotNil(t, emoji.IsValid())
+
+	emoji.Id = NewId()
+	emoji.CreateAt = 0
+	require.NotNil(t, emoji.IsValid())
+
+	emoji.CreateAt = 1234
+	emoji.UpdateAt = 0
+	require.NotNil(t, emoji.IsValid())
+
+	emoji.UpdateAt = 1234
+	emoji.CreatorId = strings.Repeat("1", 27)
+	require.NotNil(t, emoji.IsValid())
+
+	emoji.CreatorId = NewId()
+	emoji.Name = strings.Repeat("1", 65)
+	require.NotNil(t, emoji.IsValid())
+
+	emoji.Name = ""
+	require.NotNil(t, emoji.IsValid())
+
+	emoji.Name = strings.Repeat("1", 64)
+	require.Nil(t, emoji.IsValid())
+
+	emoji.Name = "name-"
+	require.Nil(t, emoji.IsValid())
+
+	emoji.Name = "name+"
+	require.Nil(t, emoji.IsValid())
+
+	emoji.Name = "name_"
+	require.Nil(t, emoji.IsValid())
+
+	emoji.Name = "name:"
+	require.NotNil(t, emoji.IsValid())
+
+	emoji.Name = "croissant"
+	require.NotNil(t, emoji.IsValid())
+}