Add sanitizer for multi-lingual names

[lonvia]

In areas where multiple languages are spoken, OSM usually has a name tag which contains all the language variants. This can for example be seen in Brussels not only in the name of the city itself but also on every street within the city. The language variants then appear again in separate language-specific name tags.

It would be nice to have a sanitizer which detects when a name tag only consists of a concatenation of names already present in language-specific name tags and removes the name in that case.

Note that the rules on how the names are concatenated are region-specific and can be complex. This wiki page list some current practice. Essentially, there are four ways of concatenating: slash, hyphen, semicolon and simple space. Ideally the sanitizer can just deal with all of them. We definitely need lots of tests derived from examples on this site.

[AaryanGupta01]

Hi @lonvia, I would love to take a stab at this issue! Could you please assign it to me? Also, if you could point me to the specific file or directory where the current sanitizers are located, that would be a huge help to get me started.

[mtmail]

Good starting point is https://github.com/osm-search/Nominatim/blob/master/docs/customize/Sanitizers.md and https://github.com/osm-search/Nominatim/blob/master/docs/develop/Sanitizer-Modules.md

[lonvia]

We don't assign issues and please read CONTRIBUTING.md before starting, in particular the section on AI use.