reflection: Fix references to symbols with no package

[murgatroid99]

This is a follow up to #2673, and fixes #2671 according to my manual testing. The new comment basically explains this change:

In files with no package, symbols are populated in the symbols table with a leading period in the key. If there is a package, the symbol does not have a leading period in the key. For simplicity, we check without the period, then with it.

CC @jtimmons

[jtimmons]

ah good catch @murgatroid99 - the "absolute vs relative" package references are definitely a bit confusing because we need to handle it on both ends (how it's inserted into the index and then how it's accessed afterwards) and it doesn't seem super consistent across those as to which reference type is used. I think #2595 would solve this as we'd be working off the source-of-truth at that point rather than trying to determine the file relationships after load-time

another thing we could do here is add an option to the service to suppress these warnings? They don't always have a material effect on a reflection client working so in some cases it might just be noise for the user

[murgatroid99]

another thing we could do here is add an option to the service to suppress these warnings? They don't always have a material effect on a reflection client working so in some cases it might just be noise for the user

I was actually thinking that maybe they should be errors instead of warnings. These warnings indicates that API responses will have incorrect dependency information, and it probably indicates a programming error, either on our part or on the part of the reflection library user.