symbols: convert KeyInfo->groups to darray

symbols: convert KeyInfo->groups to darray

Before it was a static array of size XKB_NUM_GROUPS.

The previous cleanups made this transition a bit easier. This is a
first step for removing the XKB_NUM_GROUPS hardcoded limit; but for now
we still check that the groups are < XKB_NUM_GROUPS (e.g. in
ResolveGroup and GetGroupIndex) until the keymap, etc. is worked out as
well.

This also makes us alloc quite a bit less (this is just rulescomp):
Before:
==51999==   total heap usage: 291,474 allocs, 291,474 frees, 21,458,334 bytes allocated
After:
==31394==   total heap usage: 293,595 allocs, 293,595 frees, 18,150,110 bytes allocated
This is because most rmlvo's don't use the full 4 layouts that KeyInfo
had always alloced statically before.

Signed-off-by: Ran Benita <ran234@gmail.com>