Improve credit line in image list

[whym]

Description (required)

Fixes #6264 and #5030

1. I replaced the credit line in the list of images (in contribution, explore, etc) with 3 kinds of text, in order to resolve [Bug]: Uploaded by shows what's in the source/author field, not the upload #6264 (comment)

2. I added mechanism to retrieve creator value, when needed & available. This is to resolve Author field shows HTML tags when template used #5030 and used when HTML parsing of the author field fails. (More on this below.)

Because structured data requires additional HTTP requests, I took this approach:

• First parse the HTML (which is already retrieved). If the HTML is in non-standard format (basically anything other than the HTML version of [[User:UserName|AnotherName]]), it fails.
• If fails, show the uploader only immediately. Retrieve creator label(s) from structured data, and redraw the credit line, usually half a second later.

Tests performed (required)

I mostly used an API 35 emulator with betaDebug and prodDebug. I briefly tested with Pixel 3 and prodDebug, too.

For BetaDebug: I removed the author values from file pages, and added "author" values in structured data. (Its P253075 on Beta Cluter.) The latter was shown in the contributions activity.

For ProdDebug: # 3 Featured Picture is "Blackspotted puffer (''Arothron nigropunctatus''), Anilao, Philippines". Its credit line contained an HTML fragment. It now shows "Diego Delso". (I added the creator value into the structured data.)

Screenshots (for UI changes only)

Remaining tasks to be resolved:

• author name string is frequently used on Commons, and should be supported. (It supports entity labels only for now.)
• There can be more than one uploader for one image (because an image can be overwritten), but only one is shown for now.

Less critical concerns:

• The duplicated code added in ContributionViewHolder and PagedMediaAdapter is not ideal. Not happy with more parameters being passed around to ContributionViewHolder. To resolve this, I think a large refactoring in the surrounding code is necessary. (A new ViewModel might help?)
• Class Media is getting large. Do we want to keep adding parameters to it?

[github-actions]

✅ Generated APK variants!

• 🤖 Download betaDebugAPK
• 🤖 Download prodDebugAPK

[nicolas-raoul]

Working great, thanks!