Enforce LF line endings

The repository contains various Bash scripts that rely on LF line
endings to function, not all of them with an .sh suffix. To prevent
issues due to a mismatch of line endings on Windows, conservatively
enforce that text files are checked out as-is (with LF).

.gitattributes

@@ -0,0 +1,6 @@
+# On Windows, Git defaults to checkout Windows-style and commit Unix-style.
+# As such, line endings of bash scripts are converted from LF to CRLF, with
+# the effect that when mounting the checkout into a Linux container, the
+# bash scripts can't execute because bash does not handle CR. To mitigate,
+# conservatively force ALL line endings to be retained.
+* -text