[MISC] Remove dependency of seqan3::detail::type_name_as_string in format_base.

[smehringer]

Since we need this, we need to copy it over.

Blocked by #7

Tasks:

• Copy over seqan3/utility/detail/type_name_as_string.hpp to sharg/detail/type_name_as_string.hpp and change the namespace to sharg
• Copy over the type_name_as_string unit test.
• Change the respective include in format_base.hpp from seqan3 to sharg.
• Check if all tests pass
• Tick off format_base in [FEATURE] Make the argument parser independent of seqan3. #6 since it does not include a seqan3 file anymore.