drt: metalWidthViaMap acts as a guard

[bnmfw]

Supports #7153.

Branched from #7210.

Introduces isViaCompatibleWithAP() which checks the presence of a LEF 58 MetalWitdhViaMap and if it allows for the AP to use the Via Def. This is integrated on validateAPForVia() and acts as a guard. This allows for the simplification of filterMultipleViaAccess which does not have to explicitly check for the metal width map anymore.

I don't like they way the check itself is made, I think if it was actually implemented as a map, instead of just a list we parse, it could be better, but it works.