By using some of the infrastructure in Utils::Environment. Due to
wanting to find all cmake executables in PATH and not just the
first one, we need some custom code.

Change-Id: If3161d712b9f6e659450a3d0647f83344e68ba5d
Task-number: QTCREATORBUG-14740
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Benjamin Zeller <benjamin.zeller@canonical.com>
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>