[Cherry-pick into stable/20240723] Implement preliminary support for deserializing cc1 flags in Swift modules.

[adrian-prantl]

commit 7c0ac3b622fa640648a1e55176a738282a64569c
Author: Adrian Prantl <[email protected]>
Date:   Fri Aug 9 17:59:09 2024 -0700

    Implement preliminary support for deserializing cc1 flags in Swift modules.
    
    There is no functional change on all other code paths.  Support for
    cc1 flags isn't complete.  Since cc1 flags are not stable it's not
    feasible to keep a list of all multi-arg flags, for example. It also
    makes it difficult to correctly identify where working directories and
    path remappings should applied. For all these reasons, using cc1 flags
    for anything but a local build with explicit modules and precise
    compiler invocations isn't supported yet.
    
    rdar://133249595