added emsdk and build script #333

Job	Run time
test-wasm (3.1.45)	13m 24s
test-unix (ubuntu-20.04, static_build)	2m 35s
test-unix (ubuntu-20.04, shared_build)	2m 5s
test-win (windows-2019, static_build)	4m 26s
test-unix (ubuntu-22.04, static_build)	2m 27s
test-win (windows-2019, shared_build)	3m 50s
test-unix (ubuntu-22.04, shared_build)	1m 28s
test-win (windows-2022, static_build)	3m 18s
test-unix (macos-11, static_build)	4m 1s
test-win (windows-2022, shared_build)	4m 48s
test-unix (macos-11, shared_build)	4m 11s
test-unix (macos-12, static_build)	2m 19s
test-unix (macos-12, shared_build)	3m 40s
	52m 32s

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