[simplejson,ultrajson] Implement formatters for simplejson and ultrajson (ujson)

[nhairs]

Per title

Note that both libraries have different handling of datetime.datetime and bytes objects. In the case of bytes they will error if they receive any non-printable characters. I've not yet been able to determine if there is a work around to the encoding or if it is just the decoding when testing that is the problem.

Test Plan

• run tests

[nhairs]

Based on my attempted discussion on reddit there doesn't seem to be much appetite for these alternate JSON encoders.

Given the standard library encoder doesn't have errors when encoding bytes and orjson is the most popular non-standard encoder and also doesn't have errors with bytes: I think I'll mark these two libraries as unsupported