runtime(c): classify type qualifiers, function specifiers and C23 attributes

runtime(c): classify type qualifiers, function specifiers and C23 attributes

Move const, volatile, restrict and _Atomic to a new cTypeQualifier group
and inline and _Noreturn to cFunctionSpec. Add the C23 standard attributes
deprecated, fallthrough, maybe_unused, nodiscard, unsequenced and
reproducible as cStandardAttribute, and reclassify the existing noreturn
into the same group.

The new groups link to cStorageClass, so the default highlighting and any
existing cStorageClass override are unchanged, while allowing finer-grained
customization.

fixes:  #19574
closes: #20368

Signed-off-by: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>