Move environment switcher admin form to the environment_indicator_ui module.

Problem/Motivation

When you enable the environment indicator module, and not the environment indicator ui module, it can be somewhat confusing when you have the environment switcher admin ui available.

Steps to reproduce

1. Enable the environment_indicator module via drush drush en -y environment_indicator
2. Go find the administration form for the module in order to configure and test it out.
3. Eventually find this screen.

Proposed resolution

Move the Environment Switcher UI to the environment_indicator_ui module or break it out into its own separate module.

Remaining tasks

User interface changes

API changes

Data model changes