* feat(menu): add a graphical boot menu
Adds the graphical menu style, selected with menu-style = "graphical" or
--menu-style=graphical. It draws to the graphics output with the existing
framebuffer, using a built-in 8x8 font, and takes input from the keyboard
and from relative or absolute pointers. The Sprout logo is drawn in the
bottom right corner. If there is no graphics output, the simple menu is
used, which still falls back to the basic menu.
The logo is converted from assets/logo-small.png to raw pixels by the build
crate, which adds the png crate as a build-time dependency only.
The default menu style is still simple. Pointer input is untested, as
OVMF has no mouse driver.
* fix(build): only build the logo conversion on the host
CI builds the whole workspace for the UEFI target, which also builds the
build crate for UEFI. The png dependency pulls in simd-adler32, which
crashes LLVM on that target. The logo conversion only runs in build
scripts on the host, so png and the conversion are now left out when
targeting UEFI.
alex