Ability to specify schema URL

[MebinAbraham]

What is the context of this PR?

• Added the ability to specify a schema URL instead of selecting a schema from runner.
• Specifying a URL means that the runner claims will include a survey_url field which runner will use to launch.

Note: Runner current implementation requires schema_name or eq_id and form_type. Therefore, when launching using a URL, schema name is passed for test schemas and for non test schema eq_id and form_type are passed. This is likely to change in future iterations.

How to review

Run this branch via docker or locally.
Note: You need to clear your browsers cache since the CSS has changed.

Ensure:

• you are able to specify a schema URL and launch the questionnaire. Validate runner did in fact launch using survey_url and was not loaded from file system. Use a schema that doesn't exist in runner.
• the existing behaviour of selecting from the schema list is unaffected.
• when launching using a schema URL, runner's downstream payload contains collection.schema_name.