badwords: rework exceptions, fix many of them

Also:
- support per-directory and per-upper-directory whitelist entries.
- convert badlist input grep tweak into the above format.
  (except for 'And' which had just a few hits.)
- fix many code exceptions, but do not enforce.
  (there also remain about 350 'will' uses in lib)
- fix badwords in example code, drop exceptions.
- badwords-all: convert to Perl.
  To make it usable from CMake.
- FAQ: reword to not use 'will'. Drop exception.

Closes #20886

src/tool_operate.h

@@ -75,7 +75,7 @@ struct per_transfer {
   BIT(added); /* set TRUE when added to the multi handle */
   BIT(abort); /* when doing parallel transfers and this is TRUE then a critical
                  error (eg --fail-early) has occurred in another transfer and
-                 this transfer will be aborted in the progress callback */
+                 this transfer gets aborted in the progress callback */
   BIT(skip);  /* considered already done */
 };