As mentioned in https://github.com/boa-dev/boa/pull/2848#issuecomment-1518909512, this uses our new default ICU4X data to replace `char::is_start` and `char::is_continue` from the `boa_unicode` crate with the [`icu_properties`](https://crates.io/crates/icu_properties) crate.
Note that this doesn't deprecate `boa_unicode` yet, since that'll require some discussion about how to proceed with a now unused sub-crate.
José Julián Espina