Favicon matching exploreuk-web-app

[Nealium104]

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Favicons in exploreuk-web-app have changed (currently in the limestone-rewrite). Findingaid should also change to match. Here are a few ideas already discussed:

I think we should strip findingaid of all icons, and rely on a hardcoded path to where they will be in production (or a dev environment with the findingaid profile). exploreuk-web-app provides the icons, findingaid relies on those assets existing in prod.
Stripping all references to an icon in findingaid would also fall back to exploreuk-web-app's favicon.
Alternatives would be shipping duplicated assets in findingaid or hosting them on a CDN for both exploreuk-web-app and findingaid.
The only downside to stripping them out entirely on findingaid that I can think of is that if someone adds a findingaid page to the home screen on their phone, they wouldn't get the ExploreUK icon.