✨ Open file in a new tab by default

### Description

Codeedit 0.3.6:

When opening an existing file, it is too easy to just click on the filename in the file tree displayed on the left. While this opens the file, it replaces the file which is currently open in the tab. In most cases, we want the file to be open along with the currently open ones. This can be done by doing a context click on the file name and then choose "Open In Tab".

I suggest that this "Open In Tab" becomes the default action, and having instead a context menu entry saying "Open In Current Buffer" if we want to replace the currently opened file by a new one.

### Alternatives Considered

An alternative would be to provide a setting for the editor, where we can choose between "always open in new tab" and "always open in current buffer".

### Additional Context

_No response_

### Screenshots

_No response_

No file or test is named. Start by tracing the file-tree filename click entry point and the existing "Open In Tab" context-menu action; done means clicking a file opens a new tab by default while "Open In Current Buffer" remains available in the context menu.

Written by the indexing model from the issue text.