Adding a translation will overwrite existing translations

[florisg-infosupport]

Describe the bug
If a translation key already exists, but the enduser is not aware and selects 'create new translation', then the existing values will be overwritten. This is not necessarily a problem for the main/original language, however all translated values are also reset to the original language.

To Reproduce
Steps to reproduce the behavior:

0. make sure you have multiple language files configured(otherwise why use this tool)
1. In a file select text "hello world"
2. press ctrl + p and select the Transloco: Translate selected text
3. set the key to "bug.helloworld". So far soo good.
4. Change the texts in the language files for "bug.helloworld" to "hallo wereld" or "hi world".
5. redo steps 1-3
6. see that the text in the translation files has reset

Expected behavior
Either an error or warning should occur stating that the key already exists.
Or it should only apply the key to the selected text, without actually changing the translation files if the key matches.

Desktop (please complete the following information):
not applicable. Software verion: 0.5.0