labels for issues/PRs?

[zachschuermann]

Problem: lots of issues and PRs, not categorized well, one big long list
Proposal: introduce a handful of labels which will allow us to filter issues, understand PRs/issues better at-a-glance

Prior art: https://github.com/tokio-rs/tokio/labels?page=1&sort=name-asc

Starting a thread so we can discuss some proposals on what we'd want to include.
Strawman:

1. category labels (bug, feature, performance, tests, proposal, docs, etc.)
2. area/module labels (mod-ffi, mod-ci, mod-data-skipping, mod-cdf, etc.)
3. size/expertise labels (size-L, size-M, size-S)
4. prioritization labels?
5. status labels: waiting on reporter, needs-review, etc.
6. PR-specific labels: keep our breaking-change label