[sysinfo] Add ioctl_sysinfo_get_interrupt_controller_info()

Returns information about the interrupt controller. Currently the only
information returned is the type, which may be APIC, GICv2, or GICv3. In
the future we might want to pass through more info like whether MSIs are
used etc.

TEST=sysinfo test and manually verify the values are correct on vim2,
kvm, and x64.

Change-Id: Ic1c1f7b7e1f9bbb8ba1a6dbd9023c3061b781d0f

[sysinfo] Add ioctl_sysinfo_get_board_name()

This returns the board name from the bootloader on arm64 platforms.
On x86 it the board name defaults to "pc", but a different board name
can be returned if the x86 bootloader adds a zbi_platform_id item
to the ZBI passed to the kernel.

Also fixed a problem with device_publish_metadata() not working for
devices that already exist in the device tree.

TEST: Added test to existing sysinfo test.

ZX-1775 #done

Change-Id: Ib53fcbae49656a11df59054acde0521eb64f007f

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[utest] Remove empty-string msg args from EXPECT_*() calls in C++

The msg argument to EXPECT_*() and ASSERT_*() is optional in C++ now,
so we can drop this argument when it's an empty string.

In the earlier conversions, I only converted ASSERT_*() and forgot to
convert EXPECT_*() too.

This change also converts a few ASSERT_*() instances that appeared
since the earlier changes.

MG-905

Change-Id: I034c6d6a6b614ab0b315dcd409435c9fe9e27e6c

[dev][sysinfo] Fix ioctl_sysinfo_get_root_resource

Resources are no longer enumerable, so don't duplicate the root resource
handle with MX_RIGHT_ENUMERATE.

Add a regression test to make sure the ioctl keeps working.

Broken by https://fuchsia-review.googlesource.com/c/37205/

Change-Id: I0c2ec4e4795ccee03d781e8b6df572a994714e93