✨ add data page metadata fields to admin

[Marigold]

Implementation of #2523.

Indicator page

• Add all new fields, including updatePeriodDays
• Add a list of origins for an indicator (all fields except license)
• Add indicator source (there's always max 1)

Dataset page

• Add origins to admin/api/datasets/X.json
• Add updatePeriodDays
• Add a list of origins for all indicators from a dataset
• Add a list of dataset sources and remove confusing fields that use the first dataset source

Notes

• I initially wanted to put field help text from our ETL docs into secondaryLabel, but eventually decided to only include link to our docs as the help would get outdated soon
• There's still the old confusing Source on Dataset page. Perhaps we could remove it and add sources to indicator tab instead?
• None of the fields are editable (turning editing on probably won't work for JSON fields... or maybe none of the fields)
• JSON fields like grapherConfigETL are shown as plain text
• Old indicators show empty data page metadata and empty origins (to shame us)
• Let me know if I'm misusing HTML rows / cols structure

Examples:

• Indicator with full metadata
• Indicator with some metadata
• Multiple origins for an indicator
• Old indicator without new metadata
• Dataset page
• Dataset with multiple sources
• Indicator with source

[Marigold]

@danyx23 added sources to indicator and dataset admin pages.

[danyx23]

Looks good! I think we should probably add a limit clause to the sources query for datasets. The reason is that for some extreme datasets there are hundreds or thousands of sources. Maybe limit it to 50 and add a note above or below the list?

I also removed the singular source on datasets as we no longer need it there

[danyx23]

I think we should limit the number of sources we retrieve, otherwise this is good to ship!