fix: reject was not called on timeout, decline and cancel scenarios

[santhoshvai]

Background

Currently, we don't call reject unless reject: true is passed on leave(). This was a recent change, so it caused a bug where reject was not called on timeout, decline, and cancel scenarios.

There are four predefined reasons for rejecting the call:

• busy - when the callee is busy and cannot accept the call.
• decline - when the callee intentionally declines the call.
• cancel - when the caller cancels the call.
• timeout - when the caller or callee rejects the call after auto_cancel_timeout_ms or incoming_call_timeout_ms accordingly

What has been done

• Reject is now called on timeout, decline and cancel scenarios. We dont handle busy yet. Will be part of Android telecom/callkit alignment I believe.
• Added reason to reject API call
• incoming_call_timeout_ms support has been added