Use jarl linter

[matt-dray]

jarl is way fast and we can put it in an action.

jarl.toml for config, like:

[lint]
exclude = ["data-raw/la-lookups.R"]

I don't see linters for line_length_linter(120) and object_length_linter(50). Noting:

lintr includes many rules related to code formatting, such as brace_linter, line_length_linter, and paren_body_linter, among others. Supporting those rules is not an objective of Jarl. Instead, I recommend using the Air formatter.

Edit: actually yeah, we have line-width = 120 in air.toml, so that's covered.