Update scom/opsgenie.ps1

[pganglbauer]

Added support for custom/all resolutionstate values. Currently all values except 'New' and 'Closed' are ignored although according to the docu https://support.atlassian.com/opsgenie/docs/integrate-opsgenie-with-microsoft-scom/ also resolved and acknowledged should be handled. In addition we use a custom resolution state based on which alerts in Opsgenie should be closed as well.