Allow editing the key of a translation unit/source string

### Describe the problem

I wish to change the key of a source string. This is easily done in my source files ("Find & replace"), but how can I reflect that change in Weblate? I can add and remove source strings in Weblate, but I cannot rename/change the key of a source string

### Describe the solution you'd like

A new menu item "change key":

or make the "Key" field of the source string editable:

### Describe alternatives you've considered

I could create a new string in the Weblate UI, but I would then have to update all translations manually and then remove the old string manually.
I could also re-upload all source files after renaming the key, but this would be a lot of work for many languages and it could mess with the History or Labels of the translations

### Screenshots

_No response_

### Additional context

I created my components by manually uploading the translation source files. I am not using GitHub or similar integrations.