[SR-2895] Audit and resolve the Optional-as-Any warnings in Foundation

[belkadan]

Previous ID	SR-2895
Radar	None
Original Reporter	@belkadan
Type	Bug

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug
Assignee	None
Priority	Medium

md5: 770b9f93f7f3d50495b3f19fbac47a8f

Issue Description:

Both swift-corelibs-foundation and the Apple Foundation overlay (swift/stdlib/public/SDK/Foundation) have quite a few warnings for implicit conversion of Optional to Any; it is likely that at least some of these are true issues (particularly the ones in string interpolations). Every one of these warnings should be addressed in some way.

[parkera]

This is done, and #5000 also addresses all outstanding warnings.