[dagit] Eliminate static fragments property
Remove all static fragments properties on React components, in favor of individual exports.
Unfortunately, importing components for the purpose of consuming their fragments can lead to circular dependencies, and appears to be causing issues in my code splitting experiments. I.e. importing a component to use its fragment will lead to bundling all of its dependencies even though we don't need them, resulting in duplication across chunks.
Additionally, the static properties are in some cases the only blocker to doing component-to-SFC conversions, a bunch of which I went ahead and did here.
Test Plan: Buildkite. Load Dagit to sanity check.
Reviewers: bengotow, prha, sashank
Reviewed By: bengotow
Differential Revision: https://dagster.phacility.com/D6049