Trying to make the helper work on Linux

Hey!
I discovered this helper today and this is excellent ! I'm pretty sure this could be used as a vim plugin to evaluate our selection directly on tinkerwell.
But as I'm using Linux, I first need to make this work on my machine.

So far, I haven't been in luck. It seems that using url schema: `://` to open the app doesn't work quit well with app images.
I tried passing them as arguments, with no luck. It looks like it's not recognized.

```bash
/home/clement/Applications/Tinkerwell-4.16.0_d8dc131b5c52a8a1f8d647de8cb37b7d.AppImage \
--cwd="L2hvbWUvY2xlbWVudC9Qcm9qZWN0cy90ZXN0cy90aGlua2VyaW5n" \
--scope="YToxOntzOjQ6InRlc3QiO3M6MTE6ImhlbGxvIHdvcmxkIjt9"
```
```bash
/home/clement/Applications/Tinkerwell-4.16.0_d8dc131b5c52a8a1f8d647de8cb37b7d.AppImage \
"tinkerwell://?cwd=L2hvbWUvY2xlbWVudC9Qcm9qZWN0cy90ZXN0cy90aGlua2VyaW5n&scope=YToxOntzOjQ6InRlc3QiO3M6MTE6ImhlbGxvIHdvcmxkIjt9"
```

Neither using directly with the binary
```bash
/tmp/.mount_TinkerdAli0c/tinkerwell \
--cwd="L2hvbWUvY2xlbWVudC9Qcm9qZWN0cy90ZXN0cy90aGlua2VyaW5n" \
--scope="YToxOntzOjQ6InRlc3QiO3M6MTE6ImhlbGxvIHdvcmxkIjt9"

# ... also tried with tinkerwell:// arg
```

Any idea on that would be appreciated. Thanks !

> Content of base64 encoded values:
> `L2hvbWUvY2xlbWVudC9Qcm9qZWN0cy90ZXN0cy90aGlua2VyaW5n`: `/home/clement/Projects/tests/thinkering`
> `YToxOntzOjQ6InRlc3QiO3M6MTE6ImhlbGxvIHdvcmxkIjt9` : `a:1:{s:4:"test";s:11:"hello world";}`