[roll] Roll fuchsia [starnix][aio] Refactor AIO logic into aio.rs

This CL moves the bulk of the async I/O logic from the syscall entry
points into the AIO domain objects. This change lets us make many types
and fields private to aio.rs.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1133717
Original-Revision: 00192810c7d2656bc2ac874515f1e1165200e97f
GitOrigin-RevId: 8c6a0056ed4f639a28ef26d363a427cad07527fe
Change-Id: I4ca124af3aaff991c518fea2faf66ab2e89f9c23

Author: Adam Barth

stem

@@ -11,7 +11,7 @@
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              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="7e5bfb887caa3b88e71abc8b996d6a6238a78c32"/>
+             revision="00192810c7d2656bc2ac874515f1e1165200e97f"/>
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