add languages r and rmarkdown

[mtoohey31]

A few notes:

• The queries for r files are copied from the grammar here.
• All the queries for rmarkdown inherit from markdown, though rmarkdown is basically pandoc markdown, so it has more syntax features that aren't supported by the plain markdown grammar. The plain markdown grammar is the best option we have though because pandoc markdown supports inline latex which makes it really complicated, so there's no complete tree-sitter grammar.
• rmarkdown needs to be a separate language from markdown because the language server can analyze the contents of {r} code blocks but should only be enabled in rmd/Rmd files.
• Both cases are included for file extensions because I've seen both used quite frequently.

And two questions:

• I included a shebang definition because it technically works, since R is an interpreted language, but I've never seen someone use a shebang in an R file. Any opinion on whether I should leave it or remove it?
• The generated lang-support.md file appears to use the name of the language server command for the default language server column. However, the name of the command for the language server in use here (this one, it's the only one I'm aware of) is just the R interpreter itself, and the arguments instruct it to invoke the languageserver package. Do we want to add in a workaround for this kind of situation so we can name the languageserver package specifically, or should we just leave it?

[archseer]

or should we just leave it?

Let's just leave it for now

Does the user need to install the package manually?

[mtoohey31]

Does the user need to install the package manually?

Yep, the command is:

R -e 'install.packages("languageserver")'

Is there somewhere that should be documented?

[pickfire]

Is there somewhere that should be documented?

No, if the user use the language chances are they will know, unless it requires special setup then maybe you might want to note it.

[mtoohey31]

Ok, sounds good. That's all the setup that's required.

[the-mikedavis]

For the installation docs, there's a new wiki for that here if you wouldn't mind adding in a section for R.

[the-mikedavis]

looks good! thanks

[mtoohey31]

For the installation docs, there's a new wiki for that here if you wouldn't mind adding in a section for R.

Done!

looks good! thanks

Thanks!