Add UEFI support to vmrun.sh

Adds:
-E: Use UEFI mode
-f: path to UEFI firmware image (default: path to uefi-edk2-bhyve package)
-F: UEFI framebuffer size (default: w=1024,h=768)
-L: IP to listen for VNC connections on (default: 127.0.0.1)
-P: Port to listen for VNC connections on (default: 5900)
-T: Enable tablnet device (for VNC)
-v: Wait for VNC client before booting VM

Submitted by: Shawn Webb <shawn.webb@hardenedbsd.org>
MFC after: 2 weeks
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D10378