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/onboarding.go

@@ -0,0 +1,31 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"encoding/json"
+	"io"
+)
+
+// CompleteOnboardingRequest describes parameters of the requested plugin.
+type CompleteOnboardingRequest struct {
+	InstallPlugins []string `json:"install_plugins"` // InstallPlugins is a list of plugins to be installed
+}
+
+func (r *CompleteOnboardingRequest) Auditable() map[string]interface{} {
+	return map[string]interface{}{
+		"install_plugins": r.InstallPlugins,
+	}
+}
+
+// CompleteOnboardingRequest decodes a json-encoded request from the given io.Reader.
+func CompleteOnboardingRequestFromReader(reader io.Reader) (*CompleteOnboardingRequest, error) {
+	var r *CompleteOnboardingRequest
+	err := json.NewDecoder(reader).Decode(&r)
+	if err != nil {
+		return nil, err
+	}
+
+	return r, nil
+}