BaseTools:BaseTools supports to the driver combination.

BaseTools:BaseTools supports to the driver combination.

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=1520

To save the image size without the compression, more than
one drivers can be combined into single one. When more than
one drivers are combined, their depex will be AND together.
Below is the example to combine BootManagerPolicyDxe into
DriverHealthManagerDxe.

Besides this patch, BaseTools also needs to check the module
type and make sure all module type are same. Otherwise,
BaseTools will report the error.
DRIVER INF has the parameter ENTRY_POINT
LIBRARY INF has the parameter LIBRARY_CLASS

Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>