PatternNodeRewriter: Allow matching variants

[ricardoV94]

This PR extends PatternNodeRewriter to allow multiple variants of the pattern to match, and automates the get_nodes from the tracks parameter.

log1msigm_to_softplus = PatternNodeRewriter(
    [
        (log, (sub, 1, (sigmoid, "x"))),
        (log, (add, 1, (mul, -1, (sigmoid, "x")))),
        (log1p, (neg, (sigmoid, "x"))),
        (log1p, (mul, -1, (sigmoid, "x"))),
    ],
    (neg, (softplus, "x")),
    allow_multiple_clients=True,
    values_eq_approx=values_eq_approx_remove_inf,
    tracks=[sigmoid],
)

PyTensor will canonicalize different expressions at different passes, and will not uncanonicalize some. It never does log1p(x) -> log(1 + x). It coverts neg to mul(-1, x) in canonicalize, and back to neg at specialize. Instead of fighting order we match the expressions that we know are expected at different sages. This is not the same as writting down all variants.

Nothing fancy is done to try to reason jointly about the variants. The more we push for this functionality the more scope there will be.

For instance a rewrite that has log1p in it could be automatically expanded to match log(1 + x), and the like. Not done in this PR.

The motivation for this PR was pymc-devs/pymc#8394 (comment)