Lint the shell scripts of the actions in the validation run

tools/lint-action-scripts.sh runs shellcheck and shfmt on actions/**/*.sh with
pinned tools; validate-workflows.yml runs it, and .editorconfig sets the shell
format. The tests show a shellcheck problem and a badly formatted script fail.

Refs #187
Task: MIL-012#6

.editorconfig

@@ -5,3 +5,8 @@ root = true
 end_of_line = lf
 charset = utf-8
 insert_final_newline = true
+
+[*.sh]
+indent_style = space
+indent_size = 2
+switch_case_indent = true