Allow disable the record of keystrokes (lossage)

Use 1 as the minimum value for lossage-limit; such a value
is equivalent to not recording the keystrokes: having just 1 entry,
will be overwritten with the view-lossage call itself.

* test/src/keyboard-tests.el (keyboard-lossage-limit): Update test.
* src/keyboard.c (MIN_NUM_RECENT_KEYS): Delete it.
(lossage_limit): Add security note in the doctring.
* lisp/cus-start.el (lossage-limit): Let users choose to disable
the record of the keystrokes.
* doc/emacs/help.texi (Misc Help): Update manual.
* etc/NEWS (Changes in Emacs 28.1):
Mention that it's possible to disable the record of keystrokes.
2 jobs for feature/bug#38796-lossage-limit in 41 minutes and 51 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Test
failed #6476
test-all

00:00:11

passed #6477
test-filenotify-gio

00:41:50

 
Name Stage Failure
failed
test-all Test
error: cannot lock ref 'refs/remotes/origin/master': Unable to create '/builds/emacs/emacs/.git/refs/remotes/origin/master.lock': File exists.

Another git process seems to be running in this repository, e.g.
an editor opened by 'git commit'. Please make sure all processes
are terminated then try again. If it still fails, a git process
may have crashed in this repository earlier:
remove the file manually to continue.
fatal: failed to run reflog
ERROR: Job failed: exit code 1