typescript type arguments are only supported as type in <const> / <let>

### Marko Version

6.0.120

### Details

I use type arguments on init value of a <let/*> element:
```marko
<let/myMap=new Map<string, number>()>
```

### Expected Behavior

get the same behaviors as:
```marko
<let/myMap:Map<string, number>=new Map()>
```

### Actual Behavior

Marko is unable to parse.

