DynamicTablesPkg: AML code generation for a Method

Add AmlCodeGenMethod() to generate code for a control method.

AmlCodeGenMethod ("MET0", 1, TRUE, 3, ParentNode, NewObjectNode)
is equivalent of the following ASL code:
    Method(MET0, 1, Serialized, 3) {}

Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>