support for more languages

[BrianHicks]

We should hypothetically be able to support any language in the list at https://tree-sitter.github.io/tree-sitter/#available-parsers. Instructions for contributing are in the README at https://github.com/BrianHicks/tree-grepper#supported-languages

[BrianHicks]

little note: if you take on adding a new language, please don't mark it as fixing this PR! This is gonna be pretty evergreen as new people want to use tree-grepper in different ways, and so the issue is to signal again that I'm open to adding new languages as wanted!