Add hidden preset for shop=ice_cream referencing amenity=ice_cream

[matkoniecz]

Description, Motivation & Context

these are effectively the same thing (though there were attempts to argue for obscure differences - disclaimer: I participated in these discussions) this adds no work for translators
shop=ice_cream should be supported somehow either way

BTW, I prefer shop=ice_cream over amenity=ice_cream but I guess that I should focus on more useful things than tagfiddling this one

Related issues

fixes part of #1641 - alternative would be to add this tag to list of ignored and unsupported ones

Links and data

Relevant OSM Wiki links:

https://wiki.openstreetmap.org/wiki/Tag%3Ashop%3Dice_cream

Relevant tag usage stats:

https://taginfo.openstreetmap.org/tags/shop=ice_cream

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## Test-Documentation

### Preview links & Sidebar Screenshots

<!-- Use the preview to find examples, select the feature in question and **copy this link here**.
     Find examples of nodes/areas. Find examples with a lot of tags or very few tags. – Whatever helps to test this thoroughly.
     Add relevant **screenshots** of the sidebar of those examples. -->

<!-- FYI: What we will check:
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### Wording

- [ ] American English
- [ ] `name`, `aliases` (if present) use Title Case
- [ ] `terms` (if present) use lower case, sorted A-Z
<!-- Learn more in https://github.com/openstreetmap/id-tagging-schema/blob/main/GUIDELINES.md#2-design-the-preset -->

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[matkoniecz]