[fs] Alphabetize dependencies in rules.mk

Test: Builds

Change-Id: Ie8f855f3cde1a135ae2cc119fc93d863e70a91e5

[fdio][fidl] Replace fuchsia-io hand-rolled client bindings

ZX-1919 #comment In Progress

Test: CQ (fs tests, fdio tests, blobfs tests, etc)

Change-Id: I31588bb62f5788fb9372fdc7042f42a3cae7c71c

[memfs] Don't link against trace-engine statically

trace-engine is a dynamic library.

Test: No behavior change
Change-Id: Ic384f335ebeee7164982ce1d79acbdef626fb3e8

[memfs] Build with -fvisibility=hidden

ZX-1895 #comment

Test: No behavior change
Change-Id: I63f755ea35bdc79b10140604b7b43a47c3b90823

[memfs] Split memfs into C / C++ libraries

For clients which utilize memfs to create
temporary filesystems, export a C ABI shared
library.

Internally, this C library uses a C++ library,
which is exported as source.

Change-Id: I73b95a2a2b8c4870d1b07f5f2f2525f4b0cd4e9f

[memfs] Export memfs as source

US-485 #done

Change-Id: I8d218c9d1065688c5b058d72eef045418d8bc976

[async] Move async-loop implementation to its own directory.

People keep getting confused by the relationship between async-loop
and the rest of the library. So let's fix it.

This change includes compatibility includes for loop.h to be removed
after upper layers are fixed to use the new paths.

Change-Id: I95c57be533fbd91468275bb2470890a4f10101eb

[memfs] Export memfs as a static library

Folks will use this library to create a process-local tmp directory.

Change-Id: I4eb13619101c06cbc0b3acbfdd38e39cf6d1f79f

[async] Separate fbl dependency from async_t

The C++ FIDL support library in Garnet wants to be able to use async_t
without linking against libfbl. Previously, the C declarations needed
create an async_wait_t were in the same header as code that depended on
fbl, which meant C++ clients of async_wait_t were forced to depend on
fbl.

After this change, the C++ wrappers for libasync interfaces are
separated from the core C declarations.

Change-Id: Ic172911a9dc775d5b5e540a33ce87d2dc218a3d9

[memfs][devmgr] Refactor MemFS into a library

Relocates the MemFS implementation from devmgr and splits it into
different files, depending on which Vnode type is being implemented.

Additionally, removes the unused "ioctl_vfs_mount_bootfs_vmo",
which tightly coupled the MemFS implementation with the devmgr.

Additional changes for ulib/memfs would be useful (splitting
the header, adding tests, adding documentation, etc), but
those changes are not included in this patch so the relocation
can remain simplified.

Change-Id: I66413215a4000565865c6394a09180922d82e16a