Log environment on CI machines

log-env.sh is cross-platform (works on Linux, MacOS and Windows)

log-env.ps1 is Windows-only and requirs specifying pwsh shell, but
provides some Windows-specific information, that might be useful e.g.
for MSVC builds.

scripts/log-env.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# To use this script in GitHub Actions job:
+#
+#  - name: "Log environment"
+#    shell: bash
+#    run: ./scripts/log-env.sh
+#
+# Line "shell: bash" is optional for Linux and MacOS,
+# but required for Windows; see also script: log-env.ps1
+
+set -x
+uname -a
+uname -s
+uname -m
+env