Allow configuring multiple fold levels for a file extension

I want my *.tsx files to be folded at level 1 and 2, but I haven't found a way to do so. It would be nice to be able to do something like this:
```
"autofold.types": [
  { "ext": ".tsx", "level": 1 },
  { "ext": ".tsx", "level": 2 }
]
```
or
```
"autofold.types": [
  { "ext": ".tsx", "level": [1, 2] }
]
```