(editorconfig--should-set): Eliminate `lisp-indent-offset` special case

(editorconfig--should-set): Eliminate `lisp-indent-offset` special case

Instead of treating `lisp-indent-offset` specially in
`editorconfig--should-set` (to obey `editorconfig-lisp-use-default-indent`),
use a new function `editorconfig-set-indentation-lisp-mode`
for Lisp modes.

* lisp/editorconfig.el (editorconfig--should-set): Remove `size` argument.
(editorconfig-set-indentation): Adjust calls accordingly.
(editorconfig-set-indentation-lisp-mode): New function.
(editorconfig-indentation-alist): Use it.