Add a general text cleanup and checking tool

[vkbo]

Note: This is a spin-off from isse #1043. It should be implemented in sync with #1061.

The highlight redundant spaces feature doesn't work properly if the spaces are a part of line wrapping. This issue cannot be resolved as it is an issue with the underlying Qt framework. However, the feature can be replace by a general text cleanup tool that can sort out multiple things.

Adding a GUI tool that can check for a selectable list of text issues could be added. It would iterate through the file one paragraph at a time and suggest removal of double-spaces, trailing spaces, maybe spell checking, quote symbols, etc.

While tools like this should be available from the Tools menu, it would also be convenient to add more such tools to the header or footer for easy access. The tool could even run the chosen checks in the background and report on problems like VSCode does. The list of problems could be an expandable panel below the text similar to the reference panel for the viewer.