added caching mechanism #1455

Job	Run time
collect-experiments	4s
unittest	44s
run-test (tests/ci/rand_soc.yaml)	29m 12s
run-test (tests/ci/randsoc_dumped.yaml)	32m 10s
run-test (tests/ci/vivado_bit_analysis.yaml)	13m 7s
run-test (tests/ci/vivado_bit_to_netlist.yaml)	2m 41s
run-test (tests/ci/vivado_conformal.yaml)	43s
run-test (tests/ci/vivado_ooc.yaml)	2m 15s
run-test (tests/ci/vivado_phys_netlist.yaml)	8m 54s
run-test (tests/ci/vivado_phys_netlist_cmp.yaml)	3m 11s
run-test (tests/ci/vivado_phys_netlist_error_inject.yaml)	4m 7s
run-test (tests/ci/vivado_wafove.yaml)	2m 46s
run-test (tests/ci/vivado_yosys_impl.yaml)	4m 25s
	1h 44m 19s

Provide feedback