Add fault tolerant syndrome measurement strategies

[perlinm]

For example, flag fault tolerant syndrome extraction circuits:

• https://journals.aps.org/prxquantum/pdf/10.1103/PRXQuantum.1.010302
• https://journals.aps.org/prxquantum/pdf/10.1103/PRXQuantum.5.040340

[perlinm]

Steane and Knill syndrome measurement would also work, but these require fault-tolerant state prep circuits (which are not implemented yet; #327)