[META] Add interim form state on form-based modals

[ohltyler]

Modals should persist their own form state, and only update when users explicitly want to. The following modals should follow this pattern:

• source data / ingest docs editor modal Add standalone form state for source data #445
• input transform modal - Add standalone form state for advanced transform modals #456
• output transform modal - Add standalone form state for advanced transform modals #456
• query editor modal - Add standalone form state for query editing modal #450

Prompt and query override modals leaving for now; these will likely be refactored and/or removed in later changes.

[ohltyler]

All PRs merged.