DynamicTablesPkg: Table Generator definition

DynamicTablesPkg: Table Generator definition

A Table generator is a component that implements the logic
for building a firmware table. This is typically implemented
as a library and registers itself with a table factory.

Table generators are further classified based on type of table
it generates, a namespace that signifies if the implementation
is standard or an OEM specific implementation and a table Id.

This patch introduces the definitions used for describing a
table generator.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Alexei Fedorov <alexei.fedorov@arm.com>