e2e: refactor

Refactor code in cucumber-support so that page object files do not get
out of control. Move code for particular directives and dialogs into
their own modules.

Make some static step definitions variable to accommodate future growth,
enabling more steps to be written with fewer step definitions.

Be particular when the contributor matters, and don't worry about
who is logged in when any contributor will do. Use maryAdmin for steps
that modify seed data.

Align tags with feature names.

Add a few classes to source code to make locating them in e2e tests
easier.