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/notify_admin.go

@@ -0,0 +1,80 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"database/sql"
+	"fmt"
+	"net/http"
+	"strings"
+)
+
+type MattermostFeature string
+
+const (
+	PaidFeatureGuestAccounts           = MattermostFeature("mattermost.feature.guest_accounts")
+	PaidFeatureCustomUsergroups        = MattermostFeature("mattermost.feature.custom_user_groups")
+	PaidFeatureCreateMultipleTeams     = MattermostFeature("mattermost.feature.create_multiple_teams")
+	PaidFeatureStartcall               = MattermostFeature("mattermost.feature.start_call")
+	PaidFeaturePlaybooksRetrospective  = MattermostFeature("mattermost.feature.playbooks_retro")
+	PaidFeatureUnlimitedMessages       = MattermostFeature("mattermost.feature.unlimited_messages")
+	PaidFeatureUnlimitedFileStorage    = MattermostFeature("mattermost.feature.unlimited_file_storage")
+	PaidFeatureAllProfessionalfeatures = MattermostFeature("mattermost.feature.all_professional")
+	PaidFeatureAllEnterprisefeatures   = MattermostFeature("mattermost.feature.all_enterprise")
+	UpgradeDowngradedWorkspace         = MattermostFeature("mattermost.feature.upgrade_downgraded_workspace")
+	PluginFeature                      = MattermostFeature("mattermost.feature.plugin")
+)
+
+var validSKUs map[string]struct{} = map[string]struct{}{
+	LicenseShortSkuProfessional: {},
+	LicenseShortSkuEnterprise:   {},
+}
+
+// These are the features a non admin would typically ping an admin about
+var paidFeatures map[MattermostFeature]struct{} = map[MattermostFeature]struct{}{
+	PaidFeatureGuestAccounts:           {},
+	PaidFeatureCustomUsergroups:        {},
+	PaidFeatureCreateMultipleTeams:     {},
+	PaidFeatureStartcall:               {},
+	PaidFeaturePlaybooksRetrospective:  {},
+	PaidFeatureUnlimitedMessages:       {},
+	PaidFeatureUnlimitedFileStorage:    {},
+	PaidFeatureAllProfessionalfeatures: {},
+	PaidFeatureAllEnterprisefeatures:   {},
+	UpgradeDowngradedWorkspace:         {},
+}
+
+type NotifyAdminToUpgradeRequest struct {
+	TrialNotification bool              `json:"trial_notification"`
+	RequiredPlan      string            `json:"required_plan"`
+	RequiredFeature   MattermostFeature `json:"required_feature"`
+}
+
+type NotifyAdminData struct {
+	CreateAt        int64             `json:"create_at,omitempty"`
+	UserId          string            `json:"user_id"`
+	RequiredPlan    string            `json:"required_plan"`
+	RequiredFeature MattermostFeature `json:"required_feature"`
+	Trial           bool              `json:"trial"`
+	SentAt          sql.NullInt64     `json:"sent_at"`
+}
+
+func (nad *NotifyAdminData) IsValid() *AppError {
+	if strings.HasPrefix(string(nad.RequiredFeature), string(PluginFeature)) {
+		return nil
+	}
+	if _, planOk := validSKUs[nad.RequiredPlan]; !planOk {
+		return NewAppError("NotifyAdmin.IsValid", fmt.Sprintf("Invalid plan, %s provided", nad.RequiredPlan), nil, "", http.StatusBadRequest)
+	}
+
+	if _, featureOk := paidFeatures[nad.RequiredFeature]; !featureOk {
+		return NewAppError("NotifyAdmin.IsValid", fmt.Sprintf("Invalid feature, %s provided", nad.RequiredFeature), nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}
+
+func (nad *NotifyAdminData) PreSave() {
+	nad.CreateAt = GetMillis()
+}