[Caching] Reduce the cost of computing compile job cache keys

[cachemeifyoucan]

Computing the compilation cache keys was expensive for large modules in
batch mode. The base cache key stored the entire command-line, including
the content of the file list, as a single blob that was different for
every job and every build, so each key stored a large new blob in the
CAS. The driver also computed the base key again for every output
producing input of a batch job.

This changes the following in swift and swift-driver:

• Split the base cache key into the arguments that are stable across
  the jobs in a module, the clang arguments, and the input list, each
  stored as a blob that can be shared between keys. The primary inputs
  are stored in the base key node, and the arguments of the options
  labeled with the new ArgumentIsCASID flag are added as references
  to the CAS objects instead of strings, so the new objects for each
  job are small. A labeled CAS ID that is not in the CAS is an error.
• Store the clang include tree at a fixed position in the base cache key
  and add createCASFileSystemFromCacheKey to replace
  iterateCommandLine, which is used by LLDB.
• Add swiftscan_cache_compute_keys_from_input_indices to compute the
  cache keys for multiple inputs in one call, and use it in the driver
  when available.
• Support the ArgumentIsCASID flag in swift-driver's makeOptions.

In a synthetic module with 1000 files, the CAS growth for a one line
edit goes from 86 MB to 0.7 MB when the driver computes the keys for
all the files. In a module with 2653 files, computing the cache keys
while planning a clean build goes from about 2.5s to 0.2s.

The driver change to skip the cache keys for the jobs that are batched
later is in #2227.

rdar://189417668

swift: swiftlang/swift#93076
llvm-project: swiftlang/llvm-project#14603

[cachemeifyoucan]

@swift-ci please test

[cachemeifyoucan]

@swift-ci please test windows platform

[cachemeifyoucan]

Windows test doesn't work until swift change is landed due to the new makeOption added.

[cachemeifyoucan]

@swift-ci please test windows platform

[cachemeifyoucan]

@swift-ci please test windows platform

[cachemeifyoucan]

@swift-ci please test windows platform

[justice-adams-apple]

@swift-ci please test windows

[cachemeifyoucan]

@swift-ci please test windows