Update all uses of variadic `.Cases` to use the initializer list
overload instead. I plan to mark variadic `.Cases` as deprecated in a
followup PR.

For more context, see https://github.com/llvm/llvm-project/pull/163117.

We don't want this as part of the public API, and using LLDB_LOG avoids
some warnings when compiling on Windows.

Commit 1a7b7e24bcc1041ae0fb90abcfb73d36d76f4a07 introduced a few casting
warnings and a build issue in Win32 platforms.

Trying to correct the casts to c++ style casts instead of C style casts.

This patch fixes:

  lldb/source/Host/posix/ConnectionFileDescriptorPosix.cpp:279:15:
  error: format specifies type 'unsigned long' but the argument has
  type 'file_t' (aka 'int') [-Werror,-Wformat]

  lldb/source/Host/posix/ConnectionFileDescriptorPosix.cpp:383:15:
  error: format specifies type 'unsigned long' but the argument has
  type 'file_t' (aka 'int') [-Werror,-Wformat]

This updates MainLoopWindows to support events for reading from a pipe
(both anonymous and named pipes) as well as sockets.

This unifies both handle types using `WSAWaitForMultipleEvents` which
can listen to both sockets and handles for change events.

This should allow us to unify how we handle watching pipes/sockets on
Windows and Posix systems.

We can extend this in the future if we want to support watching other
types, like files or even other events like a process life time.

---------

Co-authored-by: Pavel Labath <pavel@labath.sk>

It's not necessary on posix platforms as of #126935 and it's ignored on
windows as of #138896. For both platforms, we have a better way of
inheriting FDs/HANDLEs.

Originally added for reproducers, it is now only used for test code.

While we could make it a test helper, I think that after #145015 it is
simple enough to not be needed.

Also squeeze in a change to make ConnectionFileDescriptor accept a
unique_ptr<Socket>.

The main motivation for this was the inconsistency in handling of
partial reads/writes between the windows and posix implementations
(windows was returning partial reads, posix was trying to fill the
buffer completely). I settle on the windows implementation, as that's
the more common behavior, and the "eager" version can be implemented on
top of that (in most cases, it isn't necessary, since we're writing just
a single byte).

Since this also required auditing the callers to make sure they're
handling partial reads/writes correctly, I used the opportunity to
modernize the function signatures as a forcing function. They now use
the `Timeout` class (basically an `optional<duration>`) to support both
polls (timeout=0) and blocking (timeout=nullopt) operations in a single
function, and use an `Expected` instead of a by-ref result to return the
number of bytes read/written.

As a drive-by, I also fix a problem with the windows implementation
where we were rounding the timeout value down, which meant that calls
could time out slightly sooner than expected.

This PR is in reference to porting LLDB on AIX.

Link to discussions on llvm discourse and github:

1. https://discourse.llvm.org/t/port-lldb-to-ibm-aix/80640
2. https://github.com/llvm/llvm-project/issues/101657
The complete changes for porting are present in this draft PR:
https://github.com/llvm/llvm-project/pull/102601

Added some base #if _AIX changes for minimal lldb build.
Added a PR for clang-format changes separately, to rebase this on later:

- https://github.com/llvm/llvm-project/pull/120978

Review Request: @labath @DavidSpickett

This PR is in reference to porting LLDB on AIX.

Link to discussions on llvm discourse and github:

1. https://discourse.llvm.org/t/port-lldb-to-ibm-aix/80640
2. https://github.com/llvm/llvm-project/issues/101657
The complete changes for porting are present in this draft PR:
https://github.com/llvm/llvm-project/pull/102601

Added clang-format changes for changes related to some base #if _AIX
changes:

- https://github.com/llvm/llvm-project/pull/120979