More precise name for test data generation

We have Python code both for test code generation
(tests/scripts/generate_test_code.py) and now for test data generation.
Avoid the ambiguous expression "test generation".

This commit renames the Python module and adjusts all references to it. A
subsequent commit will adjust the documentation.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/Makefile b/tests/Makefile
index 8777ae9..57f8855 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -93,7 +93,7 @@
 $(GENERATED_BIGNUM_DATA_FILES): generated_bignum_test_data
 generated_bignum_test_data: scripts/generate_bignum_tests.py
 generated_bignum_test_data: ../scripts/mbedtls_dev/test_case.py
-generated_bignum_test_data: ../scripts/mbedtls_dev/test_generation.py
+generated_bignum_test_data: ../scripts/mbedtls_dev/test_data_generation.py
 generated_bignum_test_data:
 	echo "  Gen   $(GENERATED_BIGNUM_DATA_FILES)"
 	$(PYTHON) scripts/generate_bignum_tests.py
@@ -104,7 +104,7 @@
 generated_psa_test_data: ../scripts/mbedtls_dev/macro_collector.py
 generated_psa_test_data: ../scripts/mbedtls_dev/psa_storage.py
 generated_psa_test_data: ../scripts/mbedtls_dev/test_case.py
-generated_psa_test_data: ../scripts/mbedtls_dev/test_generation.py
+generated_psa_test_data: ../scripts/mbedtls_dev/test_data_generation.py
 ## The generated file only depends on the options that are present in
 ## crypto_config.h, not on which options are set. To avoid regenerating this
 ## file all the time when switching between configurations, don't declare