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/url.h

@@ -26,7 +26,7 @@
 #include "curl_setup.h"
 
 /*
- * Prototypes for library-wide functions provided by url.c
+ * Prototypes for library-wide functions
  */
 
 CURLcode Curl_init_do(struct Curl_easy *data, struct connectdata *conn);