[syscalls] Change vmar_... calls

- Create zx_vm_option_t type
- Change ZX_VM_FLAG_... to ZX_VM_... and make them new type.
- Change int32_t flags parameters to zx_vm_option_t options
- Make the options parameter be second.

- Modify vmar_..._old functions to keep other repos working.
Once they've all been updated these functions will go away.

ZX-2264
Test:CQ

Change-Id: I1faf4cc4e1e4dabf3d8ef680e398d83a545b0f09

[docs][syscalls] Add TODOs about documenting system call rights

ZX-2399 #comment

Test: no functional change
Change-Id: I1f285c677e2444fcf1d720d7ecbd9f490c303962

[syscalls] Update parameter types and names

This CL updates the parameter types and names for a number of syscalls
to match the Zircon System API rubric. There's more work to do to make
all the syscalls conform to the rubric, but this change is a start.

Change-Id: I218ac5e7e0cbd80a8c69fef7891ad40b78b6b407

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[docs][errors] Rename all the errors in docs/ to MX_OK and MX_ERR_*

Change-Id: I62451456a83145760c6454a619d4c699ce8e9017

[docs][syscalls] Fix all the manpages

Change-Id: Ie9ba25060f3331de8d9c178caf6332fb48fc80f5

[vmar] Accept unaligned lengths in unmap/protect

This makes the interface a little more ergonomic to use
alongside mx_vmar_map. If a non-page-aligned len is
passed in, it is rounded up to the next page.

Change-Id: I06ff5d5f19f680d98d8430e1be6ba19caadc4cc7

[vm] Implement new VM Address Region syscall interface

For compatibility, allow passing a process handle instead of a VMAR
to the vmar_map/unmap/protect calls and add usermode shims that
translate the old syscalls into the new ones.

Change-Id: I9ba29921d45f47d0d068e46e113dac1d139fce52