Feature: configurable language support and themes for diffs

[slavvvvvvv]

Prerequisites

• I have searched for duplicate or closed feature requests
• I have read the contributing guidelines

Proposal

Our CI step for copying static build assets grew from 1m-ish to over 7m-ish (partially due to our own faults, by not doing concurrent copying to s3) after we migrated over to @pierre/diffs. This is because we're copying over all ~200 language and ~30 theme chunks from shiki. In our use case, we don't really need all of them so it would be really nice if we could only pick a handful of those. Lemme know what additional context you might need if any :^)

Motivation and context

Improved consumer flexibility and customizability

[slavvvvvvv]

@amadeus sorry for pinging directly, have just picked a random contributor to tag 😅 if there's no capacity for this on the teams end would you be open to me opening a PR for this? 🙏

[amadeus]

Hey sorry for the delays, been gearing up to get the beta promoted to stable this week which probably means I won't have a lot of bandwidth this week.

I'm personally not an expert on bundling/build/infra, but I would assume that most of the pieces that are built are individual files that can be import()ed and thus could potentially be filtered out?

[slavvvvvvv]

Not a worry at all! Don't sweat looking into it if you're busy, I can look into it and report my findings back sometime this week hopefully. I believe modern bundlers/etc will accurately filter out the unused bits and pieces, but we're on webpack which isn't as smart I suppose 🤷