Many bignum tests have multiple calculated result values, so return
these as a list, rather than formatting as a string.
Signed-off-by: Werner Lewis <werner.lewis@arm.com>
Separate file is added for classes used to generate cases for tests
in bignum_core.function. Common elements of the BignumOperation class
are added to classes in a new common file, for use across files.
Signed-off-by: Werner Lewis <werner.lewis@arm.com>
