When generating API stubs with the scaffold utility using, e.g., `python -m localstack.aws.scaffold sns`,
the scaffold creates method names from operation names, which are ugly when acronyms (subsequent uppercase characters that belong together).

Example:
`CreateSMSSandboxPhoneNumber` -> `create_s_m_s_sandbox_phone_number`

it would be nicer to have `create_sms_sandbox_phone_number`

This is a limitation of this method: https://github.com/localstack/localstack/blob/1888e66b85d7e6a8ee457bc7a732984fcf7aa830/localstack/utils/common.py#L978-L979
return all(os.path.exists(f) for f in files)
    def store_cert_key_files(base_filename):
        key_file_name = "%s.key" % base_filename
        cert_file_name = "%s.crt" % base_filename
        
        
        content = load_file(target_file)
        key_start = re.search(PEM_KEY_START_REGEX, content)
        key_start = key_start.group(0)
        key_end = re.search(PEM_KEY_END_REGEX, content)
        key_end = key_end.group(0)
        key_content = content[content.index(key_start) : content.index(key_end) + len(key_end)]
        cert_content = content[
            content.index(PEM_CERT_START) : content.rindex(PEM_CERT_END) + len(PEM_CERT_END)
        ]
        save_file(key_file_name, key_content)
        save_file(cert_file_name, cert_content)
        return cert_file_name, key_file_name
    if target_file and not overwrite and os.path.exists(target_file):
        try:
            cert_file_name, key_file_name = store_cert_key_files(target_file)