Enable environment variables in svls-vscode.svlintToml.path

Hello!

I am trying to use SVLINT_CONFIG environment variable but it is not working for me. Is it possible to add support to be able to do something like this
```
{
...
"svls-vscode.svlintToml.path": "$WORKSPACE_UTIL/.svlint.toml",
}
```
seems like $ is not accepted by regex