Enforce deterministic FibonacciLFSR reductions (#4688) (#4689) #6802

Job	Run time
Integration Tests	7m 1s
Formatting	3m 11s
compile project with mill	9m 42s
ci (ubuntu-20.04, 8, 2.13.10, 2.4, firtool-1.43.0)	12m 38s
Test Chisel Scala-CLI Example	3m 34s
ci (ubuntu-20.04, 8, 2.12.17, 2.4, firtool-1.43.0)	12m 47s
Standard Library Tests (2.13.10)	1m 52s
Standard Library Tests (2.12.17)	2m 2s
check tests	1s
all tests passed	1s
publish	16m 7s
	1h 8m 56s

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