RFC: add typed hcat/hvcat array literals

Currently,

```jlcon
julia> Float32[1, 2, 3]
3-element Float32 Array:
 1.0f0
 2.0f0
 3.0f0

julia> Float32[1 2 3]
ERROR: syntax: unexpected 2 in X[] expression

julia> Float32[1; 2; 3]
ERROR: syntax: unexpected ; in X[] expression

julia> Float32[1 2; 3 4]
ERROR: syntax: unexpected 2 in X[] expression
```

With this patch,

```jlcon
julia> Float32[1 2 3]
1x3 Float32 Array:
 1.0f0  2.0f0  3.0f0

julia> Float32[1; 2; 3]
3-element Float32 Array:
 1.0f0
 2.0f0
 3.0f0

julia> Float32[1 2; 3 4]
2x2 Float32 Array:
 1.0f0  2.0f0
 3.0f0  4.0f0
```