merge rendering logic for Campaign{,Plan} changesets
use auto-resizing textarea for campaign description
encapsulate campaign plan spec form data in component
improve placeholders for Campaign{Title,Description}Field components
do not show username in new campaign form. It is not useful because the component does not look convincingly like a comment to make it clear that that's what we're going for.
remove namespace field, always use current user. Right now, the namespace field in the campaign form is not useful. Site admins always see all campaigns on the campaign list page, and non-site admins can't view any campaigns at all. It adds needless complexity to the form. This commit makes all campaigns created in the current user's namespace. When we support campaign namespaces throughout the UI, we can add this field back (or something like it).
use new ImageAutoAdjustIcon icon for campaigns. This icon better conveys "fix" and "auto" than the current icon (which is of a burndown chart going down). Also upgrades mdi-react and fixes snapshots to not depend on the particular SVG definition (which can fluctuate meaninglessly when mdi-react is updated). Example:
