dev-embedded/simavr: carry over from hamari overlay, bump to 1.8

dev-embedded/simavr: carry over from hamari overlay, bump to 1.8

Import the simavr-1.7 ebuild from the hamari overlay and bump to the
1.8 release.

The carried-over install patch redirected headers to
/usr/avr/include/simavr, which doesn't match simavr's own
simavr.pc/simavr-avr.pc (${prefix}/include) and broke pkg-config
consumers. Replaced it with a smaller patch that parameterizes the
Makefile's hardcoded "lib" install dir as INSTALL_LIBDIR, fed via
$(get_libdir) so multilib-strict passes and the binary's RPATH points
at the real install location instead of the build directory. Also
pass SIMAVR_VERSION=${PV} so the .pc files report the real version
instead of "unknown".

Also drop the dead empty RDEPEND/BDEPEND assignments and the redundant
KEYWORDS="" on the live ebuild branch, convert PATCHES to an array, and
add metadata.xml with a maintainer and GitHub remote-id.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>