Data pages: source tab hotfixes

[danyx23]

• Origin.description doesn't render line breaks in Sources and processing tab
• Combined Data published by from sources and origins might be non-unique - Duplicate mention below as "Names are repeated in This data is based on the following sources, because I used two files from the same author. Should I set this differently?"
• In the sources tab, the "link" field shows only links for the first origin, e.g. this chart (that shows only the link for population). Also, the "retrieved" field is also the one for population; in this case, there's an ambiguity, but maybe we should pick the latest date of all origins.
• The text from description_key is not being surfaced in the sources tab.

[lucasrodes]

• The indicator name in the sources tab follows the prioritisation scheme: presentation.title_public > indicator.title I think it should be presentation.grapher_config.title > display.name > indicator.title . We should be able to overwrite the indicator name shown in the sources tab. Using presentation.title_public is not ideal, because this field might not contain dimensions, as these might be in presentation.title_variant, and the name in the sources tab should contain the dimensions.
• The indicator name in the data page title follows the prioritisation scheme: presentation.title_public > presentation.grapher_config.title > indicator.title. Pablo proposes using presentation.title_public > display.name > indicator.title instead.

[lucasrodes]

On the second point in my previous comment (on how the data page title is defined), I think that for the title of the data page, we could go with: presentation.title_public > display.name > indicator.title . I don't think presentation.grapher_config.title is relevant here, as it feels chart-centric, and display.name should suffice.