Adds number of active channels to pysmurf controller check_state

[jlashner]

Description

Adds num_active_channels to the check_state session data of the pysmurf-controller.

Motivation and Context

This can be used by the scheduler to determine if a relock is necessary. If the this number is 0, a relock is required.

How Has This Been Tested?

This has not yet been tested.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.