Refactor errors in Rust?

[etiennebacher]

I think we should also review the various error types here:

r-polars/src/rust/src/rpolarserr.rs

Lines 9 to 36 in 6827afc

	pub enum Rctx {
	#[error("Failed to handle background task")]
	Background,
	#[error("The argument [{0}] caused an error")]
	BadArg(String),
	#[error("Encountered the following error when joining the thread:\n\t{0}")]
	BadJoin(String),
	#[error("Got value [{0}]")]
	BadVal(String),
	#[error("Encountered the following error in Rust-Extendr\n\t{0}")]
	Extendr(String),
	#[error("Cannot access exhausted thread handler")]
	Handled,
	#[error("Possibly because {0}")]
	Hint(String),
	#[error("Expected a value of type [{0}]")]
	Mistyped(String),
	#[error("Expected a value that {0}")]
	Misvalued(String),
	#[error("Not a valid R choice because {0}")]
	NotAChoice(String),
	#[error("{0}")]
	Plain(String),
	#[error("Encountered the following error in Rust-Polars:\n\t{0}")]
	Polars(String),
	#[error("When {0}")]
	When(String),
	}

Currently we use BadVal for wrong inputs, but I don't understand the difference between BadVal, MisValued and NotAChoice

Related to #954