Files represent either physical, filesystem-backed files, or virtual debugger-produced files.

Bug: b/145351270
Change-Id: Ib085a1244cc10dc644546d1d049d1bfa030744ff
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38895Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>