[dagit] Force cancelation from Dagit UI

Summary:
Use the new termination policy to allow forcing run cancelation from the Dagit UI. Specifically, this diff adds the behavior to bulk actions on the Runs page. In a followup, we can add the same behavior to individual termination.

On the Runs page, if I select a handful of runs, then use the bulk menu to terminate:

• If I have selected runs with canTerminate === true, show a checkbox in the termination dialog to allow forcing cancelation, with a warning. If the checkbox is checked, change the language to indicate that it will be a force-cancelation.
• If I have selected only runs with canTerminate === false, don't show the checkbox, just show the warning. The action will be to force termination for all of them.

Add a handful of storybook examples to test.

Test Plan: Storybook examples. View Runs page after kicking off a run, use bulk menu to cancel. Verify proper rendering and behavior of termination dialog.

Reviewers: dgibson, prha, johann

Reviewed By: dgibson

Differential Revision: https://dagster.phacility.com/D5699