firefox-db2pem.sh: add macOS support, tidy-ups

Cherry-picked from curl#19076
Closes curl#19086

Author: vszakats

scripts/firefox-db2pem.sh

@@ -32,7 +32,11 @@
 
 set -eu
 
-db=$(ls -1d "$HOME"/.mozilla/firefox/*default*)
+if [ -d "$HOME/Library/Application Support"/Firefox/Profiles ]; then
+  db=$(ls -1d "$HOME/Library/Application Support"/Firefox/Profiles/*default*)
+else
+  db=$(ls -1d "$HOME"/.mozilla/firefox/*default*)
+fi
 out="${1:-}"
 
 if test -z "$out"; then
@@ -55,7 +59,7 @@ certutil -L -h 'Builtin Object Token' -d "$db" | \
 grep ' *[CcGTPpu]*,[CcGTPpu]*,[CcGTPpu]* *$' | \
 sed -e 's/ *[CcGTPpu]*,[CcGTPpu]*,[CcGTPpu]* *$//' -e 's/\(.*\)/"\1"/' | \
 sort | \
-while read -r nickname; \
- do echo "$nickname" | sed -e "s/Builtin Object Token://g"; \
- echo "$nickname" | xargs -I{} certutil -d "$db" -L -a -n -- {} ; \
+while read -r nickname; do
+  echo "$nickname" | sed 's/Builtin Object Token://g'
+  echo "$nickname" | xargs -I{} certutil -d "$db" -L -a -n {}
 done >> "$out"