Adding a custom entry for trailling-whitespace

We're adding a wrapper around trailing-whitespace-fixer, which is the
default entry https://github.com/pre-commit/pre-commit-hooks/blob/main/.pre-commit-hooks.yaml#L205

So now, instead of directly call it, we are checking if is there any space
in the files, if so, then we add it to the list and we call trailing-whitespace-fixer.
if not file, then we don't execute anything and we retrieve success.

Apart of impacting positive as we're not calling by default the trailing-whitespace-fixer python script,
now we can see the files that needs to remove the whitespace.

Signed-off-by: Enrique Vallespi Gil <evallesp@redhat.com>

Author: evallesp

.pre-commit-config.yaml

@@ -5,6 +5,7 @@ repos:
     hooks:
       - id: end-of-file-fixer
       - id: trailing-whitespace
+        entry: bash -c 'affected_files=(); for f in "$@"; do grep -l "[[:space:]]$" "$f" 2>/dev/null && affected_files+=("$f"); done; if [ ${#affected_files[@]} -gt 0 ]; then trailing-whitespace-fixer "${affected_files[@]}"; exit $?; else exit 0; fi' --
       - id: mixed-line-ending
       - id: check-byte-order-marker
       - id: check-executables-have-shebangs