[CI] generalise travis-linux-install.sh

- move content to CI-linux-install.sh which is independent of Travis
- create equivalent for Github Actions (GHA)

Tools/GHA-linux-install.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+#lsb_release -a
+# find location of current script (only works in bash)
+script_dir="$( dirname "${BASH_SOURCE[0]}")"
+
+# run generic script
+RETRY=
+source "$script_dir"/CI-linux-install.sh