Honor wrapper-bound literals in the generated UDF calls

[estebanzimanyi]

A SQL-hidden trailing parameter of a MEOS call gets a literal from the generator. The generic type default (false for a bool) diverges from the value the MobilityDB PG wrapper binds: valueAtTimestamp binds strict=true, so a generated UDF built on the default returns the value at an exclusive bound where MobilityDB semantics return NULL.

hidden_arg reads the value the wrapper binds from the catalog (shape.boundArgs, provided by the MEOS-API derivation) and emits THAT for the hidden param, falling back to the generic type default when the catalog records no bound value. _java_bound translates the C literal to its Java form (true/false, L-suffixed longs, (byte) for unsigned char), returning null for forms with no direct Java literal so the fallback applies. Both emission sites — emit_single and emit_dispatch — route their hidden args through it.

Depends on MEOS-API #61 for the per-base-type boundArgs the dispatch siblings read; the change is backward-compatible and keeps the generic default until that lands.