Give Lisp control on the lossage size

Give Lisp control on the lossage size

Add a command 'lossage-size' to set the maximum
number or recorded keystrokes (Bug#38796).

* src/keyboard.c (lossage_limit):
Static variable with the current lossage size limit.
(MIN_NUM_RECENT_KEYS): Renamed from NUM_RECENT_KEYS.
Set it as 100 and use it as the minimum value for lossage_limit.
Keep the same default for the vector size as before (300).
(lossage-size): New command.
(update_recent_keys): Helper function.
(command_loop_1)
(record_char)
(recent-keys)
(syms_of_keyboard): Use lossage_limit as the vector size.

* lisp/help.el (view-lossage): Mention the new command in the docstring.
* etc/NEWS (Changes in Emacs 28.1): Announce this change.
* doc/emacs/help.texi (Misc Help): Update manual.
* test/src/keyboard-tests.el (keyboard-lossage-size): Add test.