input: Add replace action with keybinding (#2631)

Add a `Replace` action to open the search panel with the replace field
expanded.

- macOS `Cmd+Shift+F`, others `Ctrl+H` (`Cmd+R` / `Ctrl+R` is reload on
most platforms).
- The action also toggles the replace field, when the focus is already
in the search panel.
- Fallback to search only, when the input is not replaceable.
- `Tab` / `Shift+Tab` cycles between the search and the replace input,
instead of jumping back to the editor.

And 2 fixes of the search panel:

- Replace skipped every second match. The replaced match is dropped from
the matched ranges and the rest shift left by one, so the current index
must stay unchanged to point to the next match. closes #2657
- The matches were not updated on open search with a selected text,
because `set_value` does not emit `InputEvent::Change` since #2267.

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Co-authored-by: Jason Lee <huacnlee@gmail.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>