Adding CPUCore interface support

This commit introduces essential D-Bus infrastructure support for
hosting the `Item.CPUCore` D-Bus object. Additionally, it includes
getter and setter functions to enable get/set properties within the
`CPUCore` interface, such as core count and microcode.

Testing:
Unit test passed

Change-Id: I728522b34e96ee7d6609efb5746b40cf923812e8
Signed-off-by: Kamalkumar Patel <kamalkumar.patel@ibm.com>