Write CSS file as UTF-8 By not using deprecated IOUtils method. Change-Id: Id9b61b089b719c03da298e03b4df541b0dd17c3d Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.images/+/190611 Reviewed-by: Matthias Becker <ma.becker@sap.com> Reviewed-by: Alexander Kurtakov <akurtako@redhat.com> Tested-by: Alexander Kurtakov <akurtako@redhat.com>