Modify dumpsys architecture

Modify dumpsys architecture

This commit introduces a dumpsys-service which is responsible for
communication between dumpsys tool and service or application.
dumpsys-service creates a fifo pipe, and sends one of its ends to
dumpsys-agents. If agent confirms that requested application exists on
its bus, then dumpsys-service returns second end of pipe to dumpsys
tool. After that dumpsys tool can read the data written by requested
application or service.

Change-Id: I40545c260d5c9367da6af4454151293f7e3d1a3b