Add module for bignum_core test generation

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>
diff --git a/tests/Makefile b/tests/Makefile
index 57f8855..7c08f54 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -92,6 +92,8 @@
 .SECONDARY: generated_bignum_test_data generated_psa_test_data
 $(GENERATED_BIGNUM_DATA_FILES): generated_bignum_test_data
 generated_bignum_test_data: scripts/generate_bignum_tests.py
+generated_bignum_test_data: ../scripts/mbedtls_dev/bignum_common.py
+generated_bignum_test_data: ../scripts/mbedtls_dev/bignum_core.py
 generated_bignum_test_data: ../scripts/mbedtls_dev/test_case.py
 generated_bignum_test_data: ../scripts/mbedtls_dev/test_data_generation.py
 generated_bignum_test_data: