Feature: Improve argparse error messages for typed CLI args

[priitlatt]

When argparse encounters a ValueError while parsing command line arguments, it throws an ArgumentError following this scheme:

def _get_value(self, action, arg_string):
    ...
    try:
        ...
    except (TypeError, ValueError):
        name = getattr(action.type, '__name__', repr(action.type))
        args = {'type': name, 'value': arg_string}
        msg = _('invalid %(type)s value: %(value)r')
        raise ArgumentError(action, msg % args)
    ...

That is, the class name on the action type is used to generate the final error message which is shown to caller in terminal. It works well if basic types such as int, str etc are used, but it gets cumbersome as soon as more complicated custom types are defined as the action type, such as everything inheriting from TypedCliArgument in our case. For example
--altool-retries option expects an integer value, and if non-integer is specified, we get the following error message:

$ app-store-connect publish --altool-retries 10.2
usage: app-store-connect publish [-h] [--log-stream {stderr,stdout}] [--no-color] [--version] [-s] [-v] [--path artifact-path [artifact-path ...]] ...
app-store-connect publish: error: argument --altool-retries: invalid AltoolRetriesCount value: '10.2'

Note the error description

invalid AltoolRetriesCount value: '10.2'

in the above, which is not very informative for the user. The changes in this PR will make the error message appear as

app-store-connect publish: error: argument --altool-retries: invalid integer value: '10.2'

and adds possibility to define custom type messages for types which inherit fromTypedCliArgument.