Document procedure entry points and run_if

Teams that run several procedures from one codebase no longer have to rename files to main.py or guess which file a station executes.

• Added a full reference for the procedure entry point and root directory settings: accepted values, defaults for each framework, when a change takes effect, and how imports resolve for entry points in subdirectories.
• Added a monorepo guide for deploying several procedures from one repository, including procedure files with custom names.
• Documented how to run a subset of phases with OpenHTF's run_if option, and how skipped phases appear on the dashboard.