Unable to change choosenim directory
### Description

cannot change choosenim directory.
It would be nice if we could set the choosenim directory in a config file too, like nimbleDir.

### Nim Version

2.2.0
devel@96d6eee9bc33c22defb980fc0953c8e55f363ab2

### Current Output

`nim` produces:

```text
     Error: getAppFilename failed. (Error was: Unable to read /home/christian/.choosenim/current. (Error was: No installation has been chosen. (File missing: /home/christian/.choosenim/current)))
      Info: If unexpected, please report this error to https://github.com/nim-lang/choosenim
```
`nim --choosenimDir:$HOME/.local/share/choosenim/` produces:
```text
command line(1, 2) Error: invalid command line option: '--choosenimDir'
```



### Expected Output

```text
Nim Compiler Version 2.2.0 [Linux: amd64]
Compiled at 2024-10-02
Copyright (c) 2006-2024 by Andreas Rumpf
...
```


### Known Workarounds

calling `$HOME/.local/share/choosenim/toolchains/nim-2.2.0/bin/nim` directly

### Additional Information

_No response_