Support Ruby 3.4's `it` keyword

[amomchilov]

... once upstream Sorbet starts supporting it. sorbet#8375

#228 configured Prism to parse in Ruby 3.3 mode:

sorbet/parser/prism/Parser.h

Lines 19 to 20 in 082c0c9

	// The version of Ruby syntax that we're parsing with Prism. This determines what syntax is supported or not.
	static constexpr std::string_view ParsedRubyVersion = "3.3.0";

We'll need to update that to 3.4 (reference), then update the translation layer to match Sorbet.

[Tripple-A]

@amomchilov, we ran into this issue today with the unavailable support for “it” and in the process of doing some findings, I found this issue you created and your previous work on translating the “it” keyword.

From your PR, I saw that Prism already parses it as PM_IT_LOCAL_VARIABLE_READ_NODE, and the translation layer currently marks it as unreachable.

If the only missing piece is translating that node to _1 and updating the parser to 3.4 mode, I’d be happy to take a stab at it and open a PR. Is there anything else (e.g. broader Ruby 3.4 compatibility, other blockers to moving this upstream) that I should be aware of before doing so?

[amomchilov]

Hey @Tripple-A, this would be an ideal candidate for a first contribution to Sorbet!

Sorbet currently has two different parses (the legacy WhiteQuark parser being used upstream, and the Prism parser we're integrating here in our Shopify repo). Implementing support for it today would require double effort, to implement it in both parsers.

Luckily, our team is working on fully removing the Whitequark parser, which we expect to be done in the next few months. After that, it'll be a pretty straight forward addition to make!