Fix completions crash on transient exported property named 'default'

[andrewbranch]

Fixes #40991

Also includes a drive-by improvement to allow us to get a name for default or export= when the target is an identifier with parentheses, non-null assertions, type assertions, etc., instead of just a bare identifier.

[amcasey]

These all seem like sensible changes, but it's not immediately obvious to me what was actually crashing. Maybe aliased.parent was undefined?

[andrewbranch]

In this case default was an intersection property where the constituent properties had different parents. So on the intersection property, there is no parent, because it’s not clear why one parent would be favored over the other. A “real” default export should never be an intersection property, or transient at all (this was just manually named “default”), so there was no reason to treat it as an auto-importable export.