Enable application/protocol to set response timeout in CommandSender

[pan-apple]

Problem

The current CommandSender code uses a fixed timeout value for all commands.

In

CHIP_ERROR CommandSender::SendCommandRequest(NodeId aNodeId, Transport::AdminId aAdminId, SecureSessionHandle * secureSession)

    mpExchangeCtx->SetResponseTimeout(kImMessageTimeoutMsec);

kImMessageTimeoutMsec is currently 6 seconds.

Individual protocols could have different timeout requirements based on how long the peer takes to process the command, and what transport is being used for the message transmission.

For example, commands that require peer to use crypto operations (such as generate CSR) might take longer than command to toggle a light bulb.

And, commands going over CRMP vs BLE may have different timeout requirements to account for the message retries and retry timeouts.

Instead of having a fixed timeout for all applications/protocols, we should provide an API to the application/protocol to set the timeout value.

Proposed Solution

Add an API to CommandSender to set the command timeout value. The CommandSender can use the current value (kImMessageTimeoutMsec) as the default timeout, in case the application doesn't override it.

Add unit tests.

Integrate the API to individual protocols that have non-default timeout requirements.

[woody-apple]

What is required here @pan-apple ?