runtime(vim): Update base-syntax, remove old unused syntax groups. (#14146)

runtime(vim): Update base-syntax, remove old unused syntax groups. (#14146)

Remove old unused syntax groups.

- vimRegion, vimPattern and vimKeyword removed in Vim 5.3.
- vimAuSyntax, vimAutoCmdOpt, vimAutoSet and vimStatement removed in 5.6.

The following were linked in :hi commands but never defined with :syn
and, most likely, never used:
 - vimHLMod introduced in 5.0.
 - vimKeycode and vimKeycodeError introduced in 5.4.
 - vimElseif introduced in 5.6.
 - vimFold introduced in 6.4.
 - vimOperStar (and vimoperStar) introduced in 9.0.

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>