sagemathgh-37784: Speed up symmetric group simple_module_rank()
    
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Since we are going to work with a matrix $f^{\lambda} \times
f^{\lambda}$ (recall $f^{\lambda}$ is the number of standard Young
tableaux of shape $\lambda$), then we should just store the list of
standard tableaux rather than iterating over them repeatedly. This
results in a major speedup:
```
sage: from sage.combinat.specht_module import simple_module_rank
sage: %time simple_module_rank([5,3,2], GF(2))
CPU times: user 1.34 s, sys: 35.7 ms, total: 1.38 s
Wall time: 1.38 s
200
```
versus before
```
sage: %time simple_module_rank([5,3,2], GF(2))
CPU times: user 4.97 s, sys: 65 ms, total: 5.03 s
Wall time: 5.06 s
200
```

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URL: sagemath#37784
Reported by: Travis Scrimshaw
Reviewer(s): Darij Grinberg