v9 Pre-Work

[lforst]

Description

These are all the v9 tasks we can do before cutting the v9 branch.

GOOD REMINDER: Before deprecating something, update the docs so that the docs do not tell users to use deprecated APIs. The flow is:

• Add new/replacement feature
• Update docs, adding deprecation notices there and not tell users to use deprecated APIs by default
• Add the deprecation notice
• Add an entry to docs/draft-v9-migration-guide.md