Breaking: Network parameters improvements

[philips77]

This PR externalizes the network parameters from MeshNetworkManager to separate structure NetworkParameters.

Migration guide

Old code

meshNetworkManager = MeshNetworkManager()
meshNetworkManager.acknowledgmentTimerInterval = ...
meshNetworkManager.transmissionTimerInterval = ...
meshNetworkManager.incompleteMessageTimeout = ...
meshNetworkManager.retransmissionLimit = ..
meshNetworkManager.acknowledgmentMessageInterval = ...
meshNetworkManager.acknowledgmentMessageTimeout = ...

New code

meshNetworkManager.networkParameters = .custom { builder in
    builder.acknowledgmentTimerInterval = ...
    builder.transmissionTimerInterval = ...
    builder.incompleteMessageTimeout = ...
    builder.retransmissionLimit = ...
    builder.acknowledgmentMessageInterval = ...
    builder.acknowledgmentMessageTimeout = ...
}

[philips77]

The API of NetworkParameters was modified in #555.