feat: add subresource integrity to import map

[CallumNZ]

Reference: https://github.com/GeoNet/tickets/issues/19393

Changes proposed in this pull request:

• Add integrity value for js module files in import map.

Note: Tested by changing the SRI value to something wrong in the import map, the browser refuses to run it.

Adding this means we can remove all the subResourcePreload lines from www-geonet border.html, while still keeping subresource integrity for those scripts.

Production Changes

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