Merge release/2.10.4 into master (DD 2.10.4)

[MarkCalvert]

This pull request removes all DELWP-specific dataset resource list and data request functionality from the theme, including related styles, helpers, templates, and email formats. The changes streamline the codebase by eliminating DELWP dataset handling and associated UI elements.

Removal of DELWP dataset functionality:

• Deleted the DELWP dataset resource list HTML snippet (delwp_resources_list.html) that displayed DELWP dataset resources and the request access button.
• Removed all DELWP-specific SCSS styling for resource lists, access notes, data request forms, and dataset contact elements from _dataset.scss, and the corresponding compiled CSS from datavic_iar_theme.css. [1] [2]

Removal of DELWP dataset helpers:

• Deleted helper functions for identifying DELWP vector/raster data, DELWP datasets, and restricted DELWP datasets from helpers.py.

Removal of DELWP data request email templates:

• Deleted DELWP-specific email templates for data access requests in both HTML and plain text formats. [1] [2]