E0214 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0214.rs

Error E0214 needs a span_label, updating it from:

error[E0214]: parenthesized parameters may only be used with a trait
  --> src/test/compile-fail/E0214.rs:12:12
   |
12 |     let v: Vec(&str) = vec!["foo"]; //~ ERROR E0214
   |            ^^^^^^^^^

To:

error[E0214]: parenthesized parameters may only be used with a trait
  --> src/test/compile-fail/E0214.rs:12:12
   |
12 |     let v: Vec(&str) = vec!["foo"]; //~ ERROR E0214
   |            ^^^^^^^^^ only traits may use parentheses

Bonus: shrink the span to only the parenthesized expression:

error[E0214]: parenthesized parameters may only be used with a trait
  --> src/test/compile-fail/E0214.rs:12:12
   |
12 |     let v: Vec(&str) = vec!["foo"]; //~ ERROR E0214
   |               ^^^^^^ only traits may use parentheses

[munyari]

taking this

[donaldpipowitch]

@jonathandturner Do you think it makes sense to add a help hint to this error message similar to other error messages? Could be helpful for beginners.

error[E0214]: parenthesized parameters may only be used with a trait
  --> src/main.rs:13:23
   |
13 |     prev_value: Option(String),
   |                       ^^^^^^^^ only traits may use parentheses
   |                        - help: did you mean to use `Option<String>` here instead?