Multiple cameras support, any camera type on any socket/port

[alex-luxonis]

To install this branch:

1. Checkout to correct branch git checkout multi_cam_support
2. Install this version of depthai: python examples/install_requirements.py

Script used for test: tests/cam_test.py Examples:

• 3 color cameras: python3 tests/cam_test.py -cams rgb,c left,c right,c

• mono on rgb socket, color on right: python3 tests/cam_test.py -cams rgb,m right,c

• the default option (no extra args) is suitable to be used with the new https://github.com/luxonis/depthai-hardware/issues/85. It configures by default: -cams rgb,c left,m right,m camd,c

See the related PR for more implementation details: https://github.com/luxonis/depthai-core/pull/210