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

lib/easy.c

@@ -938,7 +938,7 @@ static CURLcode dupset(struct Curl_easy *dst, struct Curl_easy *src)
 static void dupeasy_meta_freeentry(void *p)
 {
   (void)p;
-  /* Will always be FALSE. Cannot use a 0 assert here since compilers
+  /* Always FALSE. Cannot use a 0 assert here since compilers
    * are not in agreement if they then want a NORETURN attribute or
    * not. *sigh* */
   DEBUGASSERT(p == NULL);