## Summary of the Pull Request
Adds user settings to adjust rendering behavior to mitigate blurry text on some devices.
## References
- #778 introduced this, almost certainly.
## PR Checklist
* [x] Closes#5759, mostly
* [x] I work here.
* [ ] We need community verification that this will help.
* [x] Updated schema and schema doc.
* [x] Am core contributor. Discussed in Monday sync meeting and w/ @DHowett-MSFT.
## Detailed Description of the Pull Request / Additional comments
When we switched from full-screen repaints to incremental rendering, it seems like we exposed a situation where some display drivers and hardware combinations do not handle scroll and/or dirty regions (from `IDXGISwapChain::Present1`) without blurring the data from the previous frame. As we're really close to ship, I'm offering two options to let people in this situation escape it on their own. We hope in the future to figure out what's actually going on here and mitigate it further in software, but until then, these escape hatches are available.
1. `experimental.rendering.forceFullRepaint` - This one restores the pre-778 behavior to the Terminal. On every single frame paint, we'll invalidate the entire screen and repaint it.
2. `experimental.rendering.software` - This one uses the software WARP renderer instead of using the hardware and display driver directly. The theory is that this will sidestep any driver bugs or hardware variations.
One, the other, or both of these may be field-applied by users who are experiencing this behavior.
Reverting #778 completely would also resolve this, but it would give back our largest performance win in the whole Terminal project. We don't believe that's acceptable when seemingly a majority of the users are experiencing the performance benefit with no detriment to graphical display.
## Validation Steps Performed
- [x] Flipped them on and verified with the debugger that they are being applied to the rendering pipeline
- [ ] Gave a private copy to community members in #5759 and had them try whether one, the other, or both resolved their issue.
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