Several problems with copy and paste content into an edited segment

Main Problem:

Copy and paste does not work from outside of translate5, if user copied before something inside translate5

To reproduce with Firefox:

• open a segment in a review task (with track changes)
• copy the source of the segment
• then go to another browser tab, e. g. deepl.com
• copy something there
• insert it into the target segment of translate5

Result: The source of the segment is inserted, not what was copied from deepl.com

Additional Problems fixed with this issue:

• Cut/Copy and paste in the editor (tags are removed completly)
• Same for copying content from the match resource panel
• tags are getting destroyed in the deleted text part when taking over matches
• after taking over a match leads to deleted tags when using ctrl-x on just a text
• pasting content into the editor when content is already selected does not replace the selected content and leads to an error with track changes