svlog: hir: Gen aux IdentExpr for `.a` ports
svlog: hir: Gen aux IdentExpr for `.a` ports

For ports with automatic connection by name, e.g. `.a`, emit an
auxiliary `IdentExpr` for the `a` identifier, such that the remaining
compiler pipeline does not require special treatment of this case.

fabianschuiki/moore,fabianschuiki/moore,fabianschuiki/moore,fabianschuiki/moore,fabianschuiki/moore