Move number parsing benchmarks into their own module

--HG--
rename : benchmarks/Benchmarks.hs => benchmarks/Numbers.hs
extra : rebase_source : 2f7bcff2cfe5158a8253a2400b00e1643df05255
extra : amend_source : 0354a0454d17f9128c34b882b28dac61e48afce1
Add some simple HTTP header parsing benchmarks
Add a Text version of the headers benchmarks

--HG--
rename : benchmarks/Headers.hs => benchmarks/HeadersByteString.hs
rename : benchmarks/Headers.hs => benchmarks/HeadersText.hs