Add regex-automata-0.4.8 benchmark

[Kobzol]

I replaced regex with regex-automata, because regex became a wrapper crate that only builds a certain public API on top of regex-automata and regex-syntax.

It is slower, especially in opt-incr, for some reason:

I created a bunch of incremental scenarios:

Looks like adding an empty block is the fastest one, then println/modifying contents of an array is similar, and interestingly reordering two enum variants is almost twice slower.

Related issue: #2024