New jit-lock-antiblink-grace feature

* lisp/jit-lock.el (jit-lock-antiblink-grace): New user-visible variable.
(jit-lock--antiblink-grace-timer, jit-lock--antiblink-l-l-b)
(jit-lock--antiblink-i-s-o-c): New helpers.
(jit-lock-mode): Tweak post-command-hook and
jit-lock-context-timer.
(jit-lock--antiblink-post-command): New helper.
2 jobs for scratch/jit-lock-antiblink in 90 minutes (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #2512
test-all

01:30:00

passed #2513
test-filenotify-gio

00:57:48

 
Name Stage Failure
failed
test-all Test The script exceeded the maximum execution time set for the job
make -C test check-expensive
make[1]: Entering directory '/builds/emacs/emacs/test'
rm -f ./*.tmp
make[2]: Entering directory '/builds/emacs/emacs/test'
make[3]: Entering directory '/builds/emacs/emacs/test'
ELC lisp/net/tramp-tests.elc
GEN lisp/net/tramp-tests.log
Pulling docker image gitlab/gitlab-runner-helper:x86_64-f100a208 ...
ERROR: Job failed: execution took longer than 1h30m0s seconds