Improve utility function for extracting point-based time series from Earth Engine

[geonextgis]

This PR improves a recently added helper function extract_timeseries_to_point() to simplify extracting time series data from a Google Earth Engine ImageCollection at a single coordinate.

⚙️ Changes & Improvements

• Modified function:

  def extract_timeseries_to_point(
      lat,
      lon,
      image_collection,
      start_date=None,
      end_date=None,
      band_names=None,
      scale=None,
      crs=None,
      crsTransform=None,
      out_csv=None,
  ):
      """
      Extracts pixel time series from an ee.ImageCollection at a point.
      """
      # Implementation ...

• start_date, end_date, and band_names are now optional; if omitted, the function uses the full image collection without filtering.

• Renamed parameter out_df → out_csv for clarity (since the output is a CSV file, not a DataFrame).