MM-11384: Add system install date information to the client config (#9218)

* MM-11384: Add system install date information to the client config

* Fixing translation text

* Fixes from Peer Review

model/system.go

@@ -16,6 +16,7 @@ const (
 	SYSTEM_ACTIVE_LICENSE_ID      = "ActiveLicenseId"
 	SYSTEM_LAST_COMPLIANCE_TIME   = "LastComplianceTime"
 	SYSTEM_ASYMMETRIC_SIGNING_KEY = "AsymmetricSigningKey"
+	SYSTEM_INSTALLATION_DATE_KEY  = "InstallationDate"
 )
 
 type System struct {