Use context robustness to get notified about GPU resets
and try to recover from them by rebuilding the rendering
pipeline.

The wide char spacers must not be drawn, like we do for regular wide
characters.

This fixes an issue with hints where it was possible that the terminal
content of highlighted hints changed between the highlighted hint update
and the activation of the hint.

This patch always validates the hint's text content against the hint
itself to ensure that the content is still valid for the original hint
which triggered the highlight.

Closes #8277.

This fixes an issue where an inline search in the left direction would
incorrectly assume that the first cell searched would not contain the
`WRAPLINE` flag, causing the second search for the match end to
terminate prematurely.

Fixes #8060.

Fix incorrect usage of the `flags` when drawing the preedit resulting
in setting the `flags`, but not actually reading the value back.

The logic to skip things was also used incorrectly, because the renderer
does that already based on the `WIDE_CHAR` flag on the cell.

Fixes: 67a433ceed (Skip whitespaces for wide chars in preedit)

Sextants are similar to quadrants and should align with them and
other box drawing, thus use builtin font to align them properly.

Part-of: #7422.

Fixes #7470.