Quotes reflect: sort the typeMembers output list and filter out non-members

[jchyb]

The typeMember currently returns a List (implying some kind of ordering), even though the order of the elements can be unpredictable. This is because the underlying methods operate on Sets, before wrapping those into a Seq. I believe the simplest solution is to just sort the obtained as part of the quotes reflect implementation: first depending on the location (which classlike contains it), then depending on if it is a type parameter (and the declaration order of it), then for non-type params lexicographically (ideally it would also be sorted by declaration order, but I can't really find the use case for that and it would easily be the costliest part). The reasons for choosing to sort are:

• rewriting the memberDenot to remember the ordering of items (like suggested in the linked issue thread) is dangerous. LinkedHashMap the only hashmap which keeps the insertion order, but it currently has no immutable version (so a simple mistake could spiral across the whole compiler, esp. easy to happen as the collected names are cached there) and it would add an ever so slight performance cost to a critical part of the compiler.
• This all might suggest that a quotes reflect specific rewrite would be better (since we end up redoing some of the calculations done as part of the lookupPrefix.typeMembers), but the costliest part, filtering through all of the declarations from all of the parents, we do not have to touch as part of this sort. We can also reuse the caches (while making sure we do not miss any type members which were included in the previous implementation), since we just sort that part lexicographically.

We also now filter out the non-existent Symbols, which can appear like in #22483. The whole reason why that happens is because after collecting the member names in memberDenots we wrap them in member to get their Denotation/Symbol. If that returns a NoSymbol, it's because we cannot access them as part of the symbol (so any kind of selection there will not work either). Because of this I am comfortable with just filtering them out.

Fixes #22472
Fixes #22483