cocotb: add fir_wb test replacing template counter tests #16

Job	Run time
Gate-Level Simulation	1m 49s
download_caravel	1m 4s
RTL Simulation	16s
download_deps (openlane)	45s
download_deps (precheck)	1m 32s
download_deps (setup-timing-scripts)	36s
download_deps (pdk-with-volare)	1m 37s
download_deps (install_mcw)	2m 35s
RTL-verification (sky130B)	1m 50s
hardening (sky130A)	47s
hardening (sky130B)	40s
RTL-verification (sky130A)	1m 55s
precheck	0s
STA	0s
	15m 26s

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