tests: add comprehensive wasm-c-api unit tests

Add enhanced test coverage for wasm-c-api functionality:
- Add wasm_extern_type testing with null input validation
- Add wasm_memory internal API tests with WebAssembly module integration
- Extend CMakeLists.txt to include new test files

Signed-off-by: Gong, Pu <pu.gong@intel.com>

Author: pugong2019

tests/unit/wasm-c-api/CMakeLists.txt

@@ -65,6 +65,8 @@ enable_testing()
 
 add_executable(wasm_c_api_test
   basic.cc
+  enhanced_gen_wasm_c_api_test.cc
+  enhanced_gen_wasm_memory_new_internal_test.cc
 )
 
 target_link_libraries(wasm_c_api_test vmlib gtest_main)