Parenthasize infix names in REPL output

I think it's probably a good idea to make it so that the output that the REPL prints looks like legal Idris syntax. This affects `:t`, `:search`, and `:apropos`. It would probably be good to reflect these changes in general evaluation output (for example, `Idris> (&&)`) as well as `:doc`.

Before:
```
Idris> :t (=)
= : A -> B -> Type
Idris> :t (+)
Prelude.Classes.+ : Num a => a -> a -> a
Prelude.Fin.+ : Fin n -> Fin m -> Fin (n + m)
```

After:
```
Idris> :t (=)
(=) : A -> B -> Type
Idris> :t (+)
(Prelude.Classes.+) : Num a => a -> a -> a
(Prelude.Fin.+) : Fin n -> Fin m -> Fin (n + m)
```