Improve the diff highlight in some cases

### Describe the problem

Diff highlighting needs improvement in some cases when only punctuation or symbols are involved (I guess).

See the example in https://hosted.weblate.org/changes/browse/osmand/ios/zh_Hans/85935031/ (https://hosted.weblate.org/translate/osmand/ios/zh_Hans/?checksum=551b111178c6a543#history)
The slash `/` should not be involved in the diff highlight for either event in the screenshot. The current diff highlight doesn’t really show that either is a `2 characters edited` event.

### Describe the solution you would like

Highlight only the spaces before and after the slash.

### Describe alternatives you have considered

_No response_

### Screenshots


### Additional context

_No response_