…_swift 2.1.1 (#906)

One of the CI error is:
```
error: generate-pch command failed with exit code 1 (use -v to see invocation)
tests/ios/unit-test/test-imports-app/TestImports-App-Bridging-Header.h:1:9: error: 'TestImports-App/Header2.h' file not found
#import <TestImports-App/Header2.h>
        ^
1 error generated.
<unknown>:0: error: failed to emit precompiled header 'bazel-out/ios-sim_arm64-min12.0-applebin_ios-ios_sim_arm64-dbg-ST-c2aefc9133a8/bin/_pch_output_dir/TestImports-App-Bridging-Header-swift_28IU2BV1DK30K-clang_1FNSWCOAS4SUQ.pch' for bridging header 'tests/ios/unit-test/test-imports-app/TestImports-App-Bridging-Header.h'
```
This is because this header was suppose to be an input to Swift compile
via hmap creation rule. But in this breaking change
bazelbuild/rules_swift@d68b214
rules_swift stopped collecting compilation context from `CcInfo` if the
target is Swift code (line 1555 of `swift/internal/compiling.bzl`).
Instead it depends on reading the same info from
`clang_module.compilation_context` which is available from `SwiftInfo`
provider (SwiftInfo -> modules -> clang)

This PR deals with header maps side where we propagate compilation
context via this `clang` module

Next step is to do the same for other places where we need to pass the
compilation context

CI for this PR should no longer produce this error (but will still fail
on some other tests)

…s_swift 2.1.1

…n framework_files.output