Change PauliFrame underlying data to be UInt32 instead of Bool

[Shayan-P]

Each Boolean value takes 1 byte (but we are using 1 bit of information here).

By using UInt32 and bitmask, we will improve the memory by 8x.

Also, this becomes a bottleneck when users want to create large Pauliframes. For example, with 6GB of RAM given those measurements=2000, I cannot go beyond setting trajectories to 2^20 (and it crashes there sometimes).