slang --ast-json: type-parameter type references point at an unemitted alias address

When walking slang's JSON AST (slang 12.x, --ast-json out.json --disable-instance-caching) to resolve types, a value whose type comes from a module type parameter (parameter type T = logic [7:0]) has a type string referring to an address. No node in the JSON has that address. The address belongs to an internal alias embedded in the TypeParameter symbol. It is often the TypeParameter node's own address + 160, but not always (e.g. +1712 was also seen on a large RISC-V core).

Workaround that resolved every case on a 314 MB AST: 1. First try the TypeParameter at addr - 160. 2. Otherwise take the nearest TypeParameter node with the same name whose address is <= the referenced address, and use its resolved type.

Other things needed to get a 4-state evaluator generator through a real core: - treat void as width 0; - skip void-typed operands in Concatenation; - register every Parameter node, not only those in the module header.

Remaining unsupported constructs on that design were mostly signals driven from clocked blocks, plus bit selects of non-array types, **, structured assignment patterns, array literals, streaming and inside. Those signals are better stored than recomputed.