Unpacked `.artifactbundle` is partially usable if treated as a `.target`, but custom linker flags are needed

### Is it reproducible with SwiftPM command-line tools: `swift build`, `swift test`, `swift package` etc? - [x] Confirmed reproduction steps with SwiftPM CLI. The description text _must_ include reproduction steps with either of command-line SwiftPM commands, `swift build`, `swift test`, `swift package` etc. ### Description An unpacked directory titled `.artifactbundle` will be treated like a normal `.target()` if an `info.json` file is found inside, however paths to link libraries and other flags are not read correctly. It is unclear how/why this is partially supported. ### Expected behavior That an unpacked `.artifactbundle` folder is treated like a proper `.artifactbundle`, or that it errors out. ### Actual behavior Undocumented and intedeterminate behavior ### Steps to reproduce 1. Unpack a `.artifactbundle` 2. Declare it's path via `.target()` 3. Add necessary `.unsafeFlag`s to link against the library stored inside it 4. Compile ### Swift Package Manager version/commit hash 6.3.2 ### Swift & OS version (output of `swift --version ; uname -a`) Swift version 6.3.2 (swift-6.3.2-RELEASE) Target: x86_64-unknown-windows-msvc Build config: +assertions