tidy-up: miscellaneous

- `N byte` -> `N-byte` or `N bytes`.
- INTERNALS.md: language tweaks.
- schannel: language tweak in comment/error message.
- socks_gssapi, socks_sspi: simplify composing an error message.
  (at a cost of 8 extra constant string bytes.)
- m4/curl-compilers.m4: fix typo in link (in comment).
- contrithanks.sh: fix indent, drop stray `;` terminator.
- lib, src, tests: drop/fix a bunch of badwords.
- fix typos in comments.
- fix indent, stray spaces.

Some of these spotted by GitHub Code Quality and Copilot

Closes #22009

docs/examples/httpput-postfields.c

@@ -40,7 +40,7 @@ static const char olivertwist[] =
   "all events; the item of mortality whose name is prefixed";
 
 /* ... to the head of this chapter. String cut off to stick within the C90
-   509 byte limit. */
+   509-byte limit. */
 
 /*
  * This example shows an HTTP PUT operation that sends a fixed buffer with