Cannot compute `sizeof` generic type in alias
### Description

```nim
type ArrayBuf*[N: static int, T] = object
  buf: array[N, T]

func maxLen(T: type): int =
  sizeof(T) * 2

type MyBuf[I: type] = ArrayBuf[maxLen(I), byte]

var v: MyBuf[int]
```

note `I: type` in alias - removing it gives #24043 instead

### Nim Version

2.0.8

### Current Output

```text
testit.nim(5, 9) Error: 'sizeof' requires '.importc' types to be '.completeStruct'
```


### Expected Output

_No response_

### Known Workarounds

_No response_

### Additional Information

_No response_