Add dialogues for context bar tiles

Finally, here’s the MR to add the dialogues from the context tiles design.

This is finished and tested, but there are probably a few areas which need some attention before it’s merged, or as follow-ups:

• The styling for the context tiles is a bit odd when you click them (I don’t know how to style completely flat buttons).
• I’m unsure whether the rows in the dialogues should be ordered by importance (colour) so the more important rows are at the top, or whether the order should always be the same regardless of the app. On the age rating dialogue the rows are sorted by importance since there are so many rows. On the other dialogues, their order is static. ⇒ discussion here
• I haven’t implemented highlighting when a runtime is out of date (on the safety dialogue, it’s the red warning triangle at the bottom of the right-most design for that dialogue) as the data currently isn’t available for that. It could be done as a follow-up, although I would suggest it’s not a priority for GNOME 41. ⇒ #1335 (closed)
• As always, some of the styling is probably off and people may disagree with my fairly arbitrary icon choices and wording choices. Specific suggestions for how to improve that are welcome.
• Dialogue widths are inconsistent due to being calculated (as per the default) from the length of label text in the rows. Perhaps a width should be specified instead? ⇒ done with Adrien’s changes

Helps: #1111 (closed)