Optimise String.starts_with?/2 (#7592)
Optimise String.starts_with?/2 (#7592)

The new implementation is 10x to 150x faster on the benchmark data.

The full benchmark: https://gist.github.com/michalmuskala/b8dea400a9902356f5bc53c201161a05
lexmag/elixir,michalmuskala/elixir,ggcampinho/elixir,kimshrier/elixir,kimshrier/elixir,pedrosnk/elixir,kelvinst/elixir,pedrosnk/elixir,kelvinst/elixir,ggcampinho/elixir,elixir-lang/elixir,joshprice/elixir,lexmag/elixir