[enhancement][dslx] Tabular comparisons (including for tuples of boolean, one-hot cases) can be cumbersome in Rustic match syntax

### What's hard to do? (limit 100 words)

As described in this comment and its followups: https://github.com/google/xls/issues/1909#issuecomment-2638570469

It's common to smash some boolean values together and make a table of how you want to handle the possibilities for that bit vector. We may want to consider better syntax for this.

(Aside: IMO ideally if we do add non-Rustic syntax there's a simple way we can describe a simple desugaring of it into a Rustic pattern match just as confirmation we're not adding anything too far afield.)

cc @proppy @ericastor @mikex-oss

### Current best alternative workaround (limit 100 words)

As described in followup comments we have things like:
```
match one_hot(sel) {
0b100 =>
0b010 =>
0b001 =>
_ => fail!("impossible_if_original_was_one_hot", ...)
}
```
which should demonstrate conclusively to the optimizer it can use a `one_hot_sel` and constructs like
```
match (x, y, z) {
(true, _, _) => ...
(_, true, _) => ...
(_, _, true) => ...
_ => ...
}
```
which lower to priority selectors on individual boolean values being set and should optimize into a prio sel primitive selector, but the OP here suggests that if this is common enough we may want to consider streamlining it.

### Your view of the "best case XLS enhancement" (limit 100 words)

Consider the addition of dedicated syntax for this (i.e. if we find it is quite common and the next-best-alternative is considered too burdensome given that frequency).