perf(cruby): reuse XPathContext objects #2568

Job	Run time
rubocop	30s
basic (ubuntu, enable)	42s
gumbo (ubuntu)	24s
gumbo (windows)	42s
gumbo (macos)	42s
jruby	1s
css parser	1s
darwin-nix	1s
libxmlruby	1s
musl	1s
rcd_image_version	1s
ruby_versions	1s
truffleruby	1s
bsd	1s
memory_suite	1s
memcheck	1s
musl-valgrind	1s
generic-package	1s
libxmlruby-valgrind	1s
cruby-package	1s
jruby-package	1s
linux	1s
osx	1s
windows	1s
cruby-install-with-setup-ruby	1s
cruby-${{ matrix.platform }}-install (${{ matrix.ruby }})	1s
generic-darwin-install	1s
cruby-${{ matrix.platform }}-install (${{ matrix.ruby }})	1s
generic-linux-install	1s
generic-windows-install	1s
cruby-x64-mingw-ucrt-install	1s
valgrind	1s
jruby-${{ matrix.jruby }}-jre${{ matrix.jre }}-install	1s
	3m 28s

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