* Corrected misspelled local variable nextHigh(t)light
* Implemented change-block navigation
* Modified behavior of the Prev/Next Change buttons in DiffView toolbar.
* Well-defined change-blocks are pre-calculated and can be navigated between.
* Current change-block is highlighted in the Diff panel(s).
* Prev/next at start/end of range (re-)scrolls to first/last change-block
(I.e when unset, or already at first/last change-block, or at the only one.)
* Current change-block is unset in RefreshContent().
* Added safeguards for edge cases
* Added indicator of current/total change-blocks in DiffView toolbar
* Added new Icon and String (en-US) for Highlighted Diff Navigation
* Added Preference and ToggleButton for diff navigation style
* input font name directly instead of a font picker because localized font family name is not supported by Avalonia
* fallback monospace font to default font
* remove unused code
* toggle amend will show changes in HEAD commit
* since discard is not compatible with staged changes in `amend` mode, we only allows user to discard unstaged changes
* replace icon with common whitespace icon in other editors
* button tooltip translations
* rename `_showHiddenSymbols` to `_showHiddenSymbolsInDiffView` to make its usage clear
* change the order of this button
* remove dotnet-tool.json because the project does not rely on any dotnet tools.
* remove Directory.Build.props because the solution has only one project.
* move src/SourceGit to src. It's not needed to put all sources into a subfolder of src since there's only one project.
