[ENH]: add path.sketch.{scale, length, randomness, seed} rcParams

Nobody has claimed this yet.

### Problem

Looking at #25796 and #26854, it might be helpful to be able to independently set the different parts of sketch and not just as a tuple. This is motivated by wanting to make `plt.xkcd` discouraged and wanting the cleanest alternative for passing in the sketch params.

### Proposed solution

#25796 moves in this direction by allowing both

```python

mpl.rcParams['path.sketch'] = (scale, length, randomness, seed)
mpl.rcParams[`path.sketch_seed'] = seed

```

and if we're OK w/ the other parameters getting their own rcParams then they can have a unified naming scheme. Alternatively, we can probably do the parsing so ``None = default`` but I don't like having to remember which position is which param.

Start by reading issues #25796 and #26854, then inspect how the existing path.sketch rcParam is handled. Decide whether scale, length, randomness, and seed should each receive independently named rcParams or use another parsing approach. Done means the chosen configuration scheme is implemented consistently and independently controls the sketch parameters.

Written by the indexing model from the issue text.