Enhance Kedro-viz doc styling by using kedro-sphinx-theme

[Huongg]

Description

To follow what @astrojuanlu has changed for Kedro doc, Kedro-viz doc also should use kedro-sphinx-theme for consistency

Possible Implementation

Possible implementation can be similar to 3675

Task includes:

• Update html_theme = "kedro-sphinx-theme" instead of html_theme = "sphinx_rtd_theme"
• Double check if some of the styling functions in docs/source/conf.py are already defined in kedro-sphinx-theme repo? If not, can we move them there to be able to reuse them?
• Update kedro-sphinx-theme packages where needed

Checklist

• Include labels so that we can categorise your feature request