Add memory_segments coverage

[gabrielbosio]

1. The VM only accepts writing arguments of type Relocatable and MaybeRelocatable. While the write_arg function accept any type, attempting to cast to a type different from the mentioned returns an error. Add a test case for calling write_arg with an invalid type.
2. Add a test case for calling gen_arg with a vector of relocatables.
3. Add a test case for calling is_valid_memory_value with a felt.