IntuneDeviceConfigurationCustomPolicyWindows10: Fix xml file payload as base64

[FabienTschanz]

Pull Request (PR) description

This pull request fixes an issue where the payload of a XML file is not encoded as base64 when uploading the data to Graph. If the XML content is not encoded as base64 and one tries to upload it to Graph, the error [ModelValidationFailure] : Cannot convert the literal '<?xml version="1.0"?>... to the expected type 'Edm.Binary' is thrown.

Please note: There is an additional PR pending that addresses an issue in the same part over on the ReverseDSC repository https://github.com/microsoft/ReverseDSC/pull/36. If possible, please look at that too.

This Pull Request (PR) fixes the following issues

None.