Move grouping in `encloseSep`

Currently `encloseSep` is defined like
```hs
encloseSep l r s ds = case ds of
[] -> l <> r
[d] -> l <> d <> r
_ -> cat (zipWith (<>) (l : repeat s) ds) <> r
```
Taking in mind that `cat = group . vcat` the last line is equivalent to
```hs
_ -> group (vcat (zipWith (<>) (l : repeat s) ds)) <> r
```
This works fine in case we want `r` to be in one line with last element:
```
[ 1
, 2
, 3 ]
```
But if we want it to be at the next line:
```
[ 1
, 2
, 3
]
```
it (with `r = line <> "]"`) won't group correctly:
```
[ 1, 2, 3
]
```
since `r` is out of `group` scope in the current definition of `encloseSep`.

I propose to change last line in the definition of the `encloseSep` in such way, that `r` will be grouped in all cases:
```hs
encloseSep l r s ds = group $ case ds of
[] -> l <> r
[d] -> l <> d <> r
_ -> vcat (zipWith (<>) (l : repeat s) ds) <> r
```
This won't change behavior when `r` doesn't contain `line` (like `list` and `tupled`), but will produce better behavior in this case.