VSCode: make "remembering" the language of the Insert Code Cell command configurable

[jimjam-slam]

Apologies for not raising this when issue #425 was discussed a few weeks ago! I understand that for most teaching contexts (probably most contexts overall, tbh), the change implemented in #540 (switching from always prompting a language to assuming the same as another, previously used code cell) is desirable and a good default.

In my case, I write a lot of mixed R/OJS Quarto docs and would appreciate the ability to restore the previous behaviour (though I don't wish to impose it on anyone else!). Having to constantly change {r} to {ojs} because I used a single R chunk at the top of the doc discourages me from using the command at all. If it's possible to make this on option that is set to the new behaviour by default, that would be fantastic!

I'd also love it if the code cell snippet had a label option pre-populated, but maybe that's being greedy 😛

[jimjam-slam]

(I should note that this isn't a showstopper for me: I can simply set up snippets manually for R and OJS! But since OJS is designed to be complementary to the render-time languages, I feel like not at least having the option to switch back-and-forth discourages its use.)