Return error on ADB connection failure

[YmBIgo]

Thanks for this great project.

While exploring codebase, I found some suspicious behaviors related to err handling and resource closing , therefore I opened PR.

---

First issue related to err handling @ runConnectionWebSocketAgentCommand & runConnectionWebrtcAgentCommand

I think code below do not exit when adb connect is failed.
Should we return err when adb connect failed? or is this intended ?

	if err := opts.ADBServerProxy.Connect(ret.Status.ADB.Port); err != nil {
		c.PrintErrf("Failed to connect ADB to device %q: %v\n", device, err)
	}

Second issue related to resource closing @ runConnectionWebSocketAgentCommand

I think code below do not close the net.Listen resource.
Should we add defer l.Close() ?

	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		c.PrintErrf("Failed to listen ADB socket: %v", err)
		return err
	}

Thank you for taking time for reading my small fix.

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[jemoreira]

Thank you for your contribution!

The return err changes do not apply, but the defer l.Close() does. In addition to fixing the PR you need to sign the Google CLA before we can merge your change, follow the instructions from the google-cla bot.

[jemoreira]

The main purpose of the function is to keep a port open that exposes the device's adb daemon in this host. This particular code instructs the adb server in this host to connect to that port. That may fail for several reasons, the most common one being no adb server is currently running; but none of those failures interferes with the main purpose of the function so the error is only logged.

[jemoreira]

same as before, this is not fatal.