`hls vscode-extension-schema` generates a wrong config type

The command outputs for wingaman hole severity option:

```
"haskell.plugin.tactics.config.hole_severity": {
"type": "string",
"scope": "resource",
"enumDescriptions": [
"error",
"warning",
"info",
"hint",
"none"
],
"default": null,
"description": "The severity to use when showing hole diagnostics. These
are noisy, but some editors don't allow jumping to all severities.",
"enum": [
1,
2,
3,
4,
null
]
},
```

but its type should be `integer` instead `string`, as we can check in the enum values. It produced abug in the vscode extension fixed when we changed the type to integer

//cc @berberman @isovector