runtime(sh): Selectively suppress matching syntax errors

runtime(sh): Selectively suppress matching syntax errors

As a refinement upon "g:sh_no_error", support not matching
particular classes of syntax errors.  Look up syntax rule
names and list them with:
‐-----------------------------------------------------------
let g:sh_no_error_rules = ["shCurlyError", "shParenError"]
‐-----------------------------------------------------------

closes: #20935

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>