Switches all imports in src to new style.

Imports are now placed on separate lines when they are full package
imports. from * imports are still on their own lines.
Includes some removal of unnecessary imports.
Updated imports in the tests.

Covers both unit and e2e tests. Updates imports to follow the convention
of independent lines for each import. Includes fixes for several imports
of components of mock and uses of mock.patch to be cleaner.
Merge branch 'refactor/import-cleanup' into dev