state-specific icons

- add html snapshots for all the states of an issue and PR (draft/open/different kinds of closed, etc)
- parse them into the spot
- render them in the table
- **hard part** - items will change state after they were sent/closed. how do we handle that?
- if we adopt #98
- we could set icon on a per-URL basis, so when the icon transitions for a given issue or PR url, we change all the icons for that URL

No files, tests, or entry points are named. Start by tracing how issue and pull-request states are parsed and rendered in the table, then examine how the proposed #98 per-URL approach could handle later state changes. Done means HTML snapshots cover the listed states, those states produce the expected icons, and transitions update all icons for the same URL.

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