autofmt removes blank lines between proc/struct/enum members

**Describe the bug**
Maybe more but I noticed that these aggregates aggressively strip blank lines, whereas functions preserve a single blank line which may be intentional for readability to denote logical separation of code.

**To Reproduce**
Run the following code through the autoformatter:

```
proc my_proc {
// foo section
// x data
foo_x: chan out;
// y data
foo_y: chan out;

// bar section
// x data
bar_x: chan out;
// y data
bar_y: chan out;

// baz section
// x data
baz_x: chan out;
// y data
baz_y: chan out;
...
}
```

See the code reformatted to:

```
proc my_proc {
// foo section
// x data
foo_x: chan out;
// y data
foo_y: chan out;
// bar section
// x data
bar_x: chan out;
// y data
bar_y: chan out;
// baz section
// x data
baz_x: chan out;
// y data
baz_y: chan out;
...
}
```

Same behavior can be seen in enum and struct definitions.

**Expected behavior**
The autoformatter should preserve the notion of subsections within these composites. It already does for code within functions, e.g.

```
fn my_function() {
// some code block
let foo = u32:1;
let bar = u32:0;

// return the sum
foo + bar
}
```

does not get reformatted to:

```
fn my_function() {
// some code block
let foo = u32:1;
let bar = u32:0;
// return the sum
foo + bar
}
```

though it would remove extra blank lines beyond 1.