Add support for disabling BigBlueButton Learning Dashboard via API (disabledFeatures)

BigBlueButton 3.x introduced a new API parameter called disabledFeatures for the
create call. This allows integrators to selectively disable certain UI components for a meeting —
including the Learning Dashboard (learningDashboard).

For many use cases, especially where privacy requirements are strict or analytics features should be limited,
being able to control this per meeting is important.

At the moment, the Drupal BigBlueButton module does not expose this option in the meeting configuration UI and
does not pass the parameter through to the BigBlueButton API.

Why this matters

• Allows disabling the Learning Dashboard on a per-meeting basis.
• Supports organizations with strict privacy or compliance requirements.
• Provides better feature parity with other BigBlueButton integrations (e.g. Moodle).
• Avoids having to disable features globally on the BigBlueButton server.

Proposed improvement

• Add a checkbox list to the meeting configuration form (global and/or per meeting) for selectable
  disabled features, for example:
  • learningDashboard
  • sharedNotes
  • polls
  • other features supported by the configured BigBlueButton version
• Pass the selected values to the BigBlueButton API as a comma-separated list, e.g.:

  disabledFeatures=learningDashboard,polls,sharedNotes

• Add a short section to the module documentation/README about:
  • the disabledFeatures parameter,
  • version requirements on the BigBlueButton side,
  • and how the feature interacts with per-meeting vs. global settings.

Notes

• In BigBlueButton 3.1 there is an upstream issue where the Learning Dashboard may still appear
  even when learningDashboard is added to disabledFeatures. This is a BigBlueButton-side
  bug, but the Drupal module should still support the parameter for current and future versions.
• This improvement would allow site builders to control the behavior directly from Drupal without
  server-level configuration changes.