Test compatibility updates for Swift Build BSP backend

[owenv]

• Update an progress message assertion which differs slightly between build system backends
• Update an output path assertion which differs between backends
• Update two tests to build before making cross-module definition requests in an Objective-C package. Previously, the native build system would construct module maps at build planning time. Swift Build generates these during the build (or preparation build). This is a behavioral change, but the new behavior is in general much better for performance and the correctness of incremental builds, so I don't think we want to try applying some hack to avoid the build/preparation here.

[owenv]

@swift-ci test

[owenv]

There's some inconsistency in whether definition requests return a range or position depending on if the index is populated I need to sort out here