add pipe operator

[q60]

it works but help needed, i'm in love/hate relationships with tree-sitter specifically and parsers in general

[qm3ster]

Should probably have the left pipe as well?

[q60]

@qm3ster i'm still waiting for some kind of review/approval of changes that i made albeit it's just 2 added lines to grammar.js
sure it works, parses with no errors, but should it have the same precedence as a concatenation operator..?

[qm3ster]

++ binds stronger than |>, you can check by doing
[1] |> (x: x) ++ [2] and [1] ++ (x: x) <| [2] in nix repl
(it fails because it tries to concatenate with the function, instead of applying it)

[q60]

seems to be working fine, i've checked parsing and highlighting a bunch of stuff. also checked on my code in helix. precedence and associativity set according to https://github.com/NixOS/nix/blob/master/doc/manual/source/language/operators.md

needs thorough testing i guess... i don't know how to test this nor to write tree-sitter tests in compliance with best practices. included test file does not work, but it would be nice to have at least something on the level of rnix-parser and nil parser tests. please excuse me as i am inexperienced in this field looking wide-eyed at all these parsers... i don't know what am i supposed to do lol