new command: `run_dosh`

Sometimes I want to run a separate dosh config from another one. This can be in my file path or in a public url.

```lua
cmd.run_dosh(
    "https://raw.githubusercontent.com/gkmngrgn/emacs.d/main/dosh.lua",
    {task = "install", parameters = "--noconfirm"}
)
```

Additionally it may be a good idea to rename `run_url` command with `run_bash` or something else.