Add tests for Julia

[schrimpf]

Begin to address #3965

These are simple ports of the existing Python tests. I don't know enough typescript to add anything more novel. In particular, on my machine, the tests do not trigger #2539 , even though running quarto render julia.qmd from a shell fails unless the --no-execute-daemon option is added.

• filed a contributor agreement.
• referenced the GitHub issue this PR closes
• updated the appropriate changelog

[cscheid]

Thank you! This is already helpful. One way to attempt to trigger #2539 is to brute-force a call to quarto render julia.cmd from a top-level Deno.test(). We try hard to keep to our own test library to manage (eg) asset cleanups but for sporadic checks like this, that's worth it.

[jjallaire]

Note that I've received the contributor agreement for this