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_sdecls.h

@@ -42,7 +42,7 @@
  * 'regular_file' member is TRUE when output goes to a regular file, this also
  * implies that output is 'seekable' and 'appendable' and also that member
  * 'filename' points to filename's string. For any standard stream member
- * 'regular_file' will be FALSE.
+ * 'regular_file' is FALSE.
  *
  * 'fopened' member is TRUE when output goes to a regular file and it
  * has been fopen'ed, requiring it to be closed later on. In any other