Clang format scripts as in MR

Add scripts to check and apply (including commit) same format sequence as in MR

Related to new section in Redmine wiki advising user to set upstream, check changes proposed by clang-format and apply them after doing hand edit where necessary

TO CHECK: The scripts right now check on hard-coded version of clang format 11.0.0

scripts/apply-format-changes.sh

+#!/bin/bash
+
+if [[ -z $GIT_CLANG_FORMAT_BIN || -z $CLANG_FORMAT_BIN ]]; then
+  echo "Error: GIT_CLANG_FORMAT_BIN or CLANG_FORMAT_BIN not defined"
+  echo "=> Please follow the instruction at https://redmine.cbm.gsi.de/projects/cbmroot/wiki/Clang-format"
+  exit -1
+fi
+
+# Check clang-format version
+VERSION=$($CLANG_FORMAT_BIN --version)
+if [[ "$VERSION" != *"11.0.0"* ]]; then
+  echo "Error: CLANG_FORMAT_BIN version not matching the standard cbmroot one (used in the MR test chain)"
+  echo "11.0.0 vs " $VERSION
+  echo "=> Please follow the instruction at https://redmine.cbm.gsi.de/projects/cbmroot/wiki/Clang-format"
+  exit -1
+fi
+
+FAIRROOT_FORMAT_BASE=upstream/master
+BASE_COMMIT=${FAIRROOT_FORMAT_BASE:-HEAD}
+CHANGED_FILES=$(git diff --name-only $BASE_COMMIT | grep -E '.*\.(h|hpp|c|C|cpp|cxx|tpl)$' | grep -viE '.*LinkDef.h$')
+
+
+$GIT_CLANG_FORMAT_BIN --verbose --commit $BASE_COMMIT $CHANGED_FILES --extensions h,hpp,c,C,cpp,cxx,tpl
+git status
+echo "Next step: git add "$CHANGED_FILES
+echo 'Then     : git commit -m"Apply clang-format"'