[Enhancement]: Convert `ds.temporal._get_weights()` to a public method

[tomvothecoder]

Is your feature request related to a problem?

This method should be turned public, similar to the ds.spatial.get_weights() method.

Describe the solution you'd like

• Remove the references to class attributes (e.g., self.freq, self.mode) and make them method arguments.
• Update downstream private methods to replace class attribute refs to method args

Describe alternatives you've considered

No response

Additional context

Also ds.spatial.get_weights() method should be listed in the API Reference page.