[dagit] Improve timestamp consistency and localization
Use toLocaleDateString for formatting our timestamps, which allows us to use the user's locale settings to determine the correct timestamp format.
A couple of time rendering options are available, namely rendering seconds and rendering the short version of the timestamp itself.
Additionally, remove the UTC-specific default formatting. My thought here is that a user should be able to use UTC as their timezone while still getting a local timestamp format string.
Jest test to validate correct rendering for same-year vs. different-year.
Load Dagit in various locales (en-US, de-DE, hu-HU). Click around and verify that timestamp strings are correctly localized.
Reviewers: bengotow, prha, dgibson, sashank
Reviewed By: dgibson
Differential Revision: https://dagster.phacility.com/D6682