Filling in VkFormat and VkImageLayout values

Fixes skia-python#350

See
   skia-python#350
   Segfault on pytest exit in CI against pybind11 3.0.1

This is a workaround. See upstream issues:

    pybind/pybind11#5976
    [BUG]: Crash due to invalid free during cleanup, if any enum is registerd, due to attempting to free a string literal

    pybind/pybind11#5991
    [BUG]: segfault at exit since upgrading to 3.0.x, probably due to "Make wrapped C++ functions pickleable" (pybind/pybind11#5580)

Signed-off-by: Hin-Tak Leung <htl10@users.sourceforge.net>

Author: Hin-Tak Leung