[compiler.h][fs] Remove DISABLE_THREAD_ANNOTATIONS from compiler.h

This mechanism is used by some filesystem code to conditionally
disable thread annotations. This is done for the sake of also building
code on the host.

This logic is specific to the filesystem code, and should not be part
of the public Zircon ABI. As such, this CL moves the conditionals into
the filesystem code itself.

Test: built with all compilers; CQ for mac; manually broke threading
analysis to verify that clang is still running the instrumentation.

Change-Id: I9c6453198c637fd03c1238d1c9790cb69ba11b6a

[fs] Avoid inlining BlockTxn, create host ulib/fs library

Test: CQ

Change-Id: I70db599252fcc0620e69cf6ce4a35cece628a261

[fzl] Move fs::MappedVmo to fzl::MappedVmo

This is a useful utility outside of the scope of just filesystems.

Change-Id: Id9cfa3d40e7d45dd6dd94242c1a85204f1139bfa
Tested: Run `runtests`

[host] package host tools needed by SDK consumers.

This CL adds the following tools:
* bootserver
* fvm
* merkleroot
* minfs
* mkbootfs
* mkfs-msdosfs
* netaddr

ZX-1712

Change-Id: I52c00d8d6deb86809f9f07771b3bf12eefa26c04

[blobfs] [minfs] [host] Combine common functionality between tools

De-dupe code between the minfs and blobfs host side tools as much as
possible. Additionally, add minfs support for adding manifests on create.

ZX-2033 #done

Change-Id: I0ece73d37927e6589ccd7d1ce235fc484668a221

[minfs][blobstore][fvm] Relocate host-side tools to /host

Change-Id: I21e3f17a7dd926dc5038af85edc0e2e016d220bd