[SR-10791] `ResolvedProduct.containsSwiftTargets` needs to recursively consider dependencies when Clang targets can depend on Swift targets

[jckarter]

Previous ID	SR-10791
Radar	None
Original Reporter	@jckarter
Type	Task

Additional Detail from JIRA

Votes	0
Component/s	Package Manager
Labels	Task
Assignee	None
Priority	Medium

md5: 91a2db20d6bbceaae4b09e92f8c08f24

Issue Description:

The `ResolvedProduct.containsSwiftTargets` helper added in #2134 currently only considers top-level targets of the product. It would need to recursively check dependencies once C targets are able to depend on Swift ones.