replaces the old focus-on-open option with a more generic focus-on
options that can be extended.
adjust the only platform that uses that option.
Fixes#8337
the render size cached in ctx->vo->dwidth/dheight can be outdated in
some circumstances at the time the context needs resizing. instead use
the current render size.
this logic was copied from the cocoa-cb opengl backend, since it was
assumed both layers work similar. apparently they don't and a nil value
on the metal layer means use the display colour profile, while on the
opengl layer it means undefined behaviour.
this also fixes a problem with the target-colorspace-hint option, since
moltenvk needs to set this colour space itself for a proper hint. both
mechanism would compete to set the colour space.
this is apparently something that was added with swift 5.5, though it is
hard to find anything officially.
don't capture self in closure but explicitly access all variables by
prepending self.
Fixes#12653
add support for vulkan through metal and a translation layer like
MoltenVK. also add the possibility to use different render timing modes
for testing.
i still consider this experimental atm.
der richter