LibWeb/WebAudio: Implement AudioNode::connect()

[Prospero23]

Sets up the basic infrastructure for the audio node graph and implements the AudioNode connect() method with its related overides. AudioNodes store vectors of AudioNodeConnections and AudioParamConnections to represent links between nodes.

[Prospero23]

The existing AudioNode WPTs just check if connect() returns the proper value or correct exception. They do not confirm that the internal C++ vectors are actually being updated when nodes are added/deleted from the audio graph.

Since the Web Audio spec doesn't expose any API on AudioNode to enumerate current connections, I am not sure the best way to write a C++ test that makes sure state is actually being updated on add or removal of a node.

The best way I can think of is to just add some debug/test methods to the public API to check to see that connections (and disconnections) are actually made by looking at the private m_input_connections, m_output_connections, and m_param_connections.

If that seems like a good idea, I am happy to add it to this PR!