Create a special ug_sources parameter for use in integrations

[obulat]

Problem

Currently we exclude some sources from the Openverse integrations. The sources list can change over time, and updating it everywhere can be tedious and time-consuming.

Description

Create a special value for the source parameter, ug_sources (user-generated sources, looking for a better name), that would be set in the API layer to the sources that are user-generated and should be filtered out to ensure that the API returns non-sensitive results. The build_search_query would then convert this special parameter to a list of the sources that we have marked as sources to filter out from integrations.

Alternatives

Update the integrations individually. This would be tedious and would require much more work for updates.

Additional context

This change could also improve the query performance because currently the integrations use a very long list of sources in filters.

[firatbezir]

i can take a look at this, @obulat could you please specify the path for this issue?

[obulat]

i can take a look at this, @obulat could you please specify the path for this issue?

It would be better if you took one of the "help wanted" issues, @firatbezir ,as those usually have a more clear scope