These are identified by misc-include-cleaner.  I've filtered out those
that break builds.  Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.

KnownIncludes is of DenseMap<StringRef, HeaderType>, so we don't need
to allocate a temporary instance of std::string.

Some `FileManager` APIs still return `{File,Directory}Entry` instead of
the preferred `{File,Directory}EntryRef`. These are documented to be
deprecated, but don't have the attribute that warns on their usage. This
PR marks them as such with `LLVM_DEPRECATED()` and replaces their usage
with the recommended counterparts. NFCI.

A few verification checks need to happen until all AST's have been
traversed, specifically for zippered framework checking. To keep source
location until that time valid, hold onto to references of
FrontendRecords + SourceManager.

* Capture reexported libraries, allowable clients, rpaths, shared cache
eligibility.
* Add support for select Xarch options.
* Add diagnostics related to capturing these options.
* Add support for verifying these attributes against what is encoded in
the dylib.

This reverts commit b7d8c6188986f62573b9516fe27fdd0c7df1aaf9. And
This reverts commit 2d40f179124f874aca4cf1145fdbc42fb8fb17f3.

It caused a build failure i'll need to reproduce.
` error: could not convert ‘Rule’ from ‘llvm::Regex’ to ‘llvm::Expected<llvm::Regex>’`

InstallAPI takes a json list of headers that is typically generated from
a build system like Xcode based on a project's attributes. Sometimes,
maintainers may want to alter this for tapi input. Using e.g.
`--extra-public-headers`, users can manipulate what headers will be used
for TBD file generation.

This adds basic support for calling the verifier on global declarations
that are expected to represent symbol exports. The driver now
exclusively uses this for knowing what symbols make up a TBD file.
Future patches will check against the dylib's symbol table.

Before it gets too unwieldy, add a common header for all MachO types
that are used across InstallAPI. Also, break up the types in
`InstallAPI/Frontend`. This both avoids circular dependencies and is
logically easier to maintain as more functionality gets added.