[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

[vim-display][display-test] Support NV12 layers

The single fullscreen layer can now use an NV12 image.

Test: display-test

Change-Id: Ie85f91bb4b1ecd5e476012af14fc9d872cccfc46

[zx] Migrate libzx off legacy_unowned<T> and update call-sites.

- Migrate APIs like zx::process::self() from returning a
|const zx::legacy_unowned<T>| to returning |zx::unowned<T>|.
- Update callers of those APIs to use the appropriate dereference
operator to access members of T, or to get a |const T&| to pass to
libzx-wrapped syscalls.
- Remove the zx::legacy_unowned<T> template.

Bug: ZX-2310
TEST=CQ
Change-Id: Idd4267cd0246ec9ab0e6f1392efe7fda45ff169d

[display] Add support for color layers

Test: display-test
Change-Id: I270351824d264e5c905a74b43a2c09079059bd94

[display] Implement new vsync API

This change adds a new vsync event to the display controller API removes
the present signal event. It also changes the behavior of the cursor
position API to clamp the cursor to the display, to sidestep the issue
of how vsync interacts with a cursor that isn't on the display.

Test: display-test, vkcube, vkcube_image_pipe_swapchain
Change-Id: I6f332e3709eef2c6e1c932581024c2149b65a2a1

[display] Add layer alpha API

Test: manually run display-test
Change-Id: I8d6791f5ad286d54bca130e0d156010e61c3539d

[display-test] Add test for hardware cursor

Test: Manually run display-test
Change-Id: I21b1b5e63e67474c1e6ab04be01b64b76b0aaf7b

[syscalls] Remove read_status from zx_channel_call

This parameter no longer has a purpose. Also, remove ZX_ERR_CALL_FAILED.
This status code no longer has a purpose.

Test: No behavior change
Change-Id: I71945ea9d1d6d591a20476106df1e598dfaf97b1

[display-test] Add test for layer rotation

This change also uses Y legacy tiling on x64 platforms, since linear
planes cannot be rotated.

Test: self
Change-Id: I51940203a9a856cbd5e540aafe03bf21207044f0

[display-test] Add tests for layers

Test: self
Change-Id: I11224c7ce7ada9913dfb7b28184215d66ebb3ba7