Add help suggestion for semicolon used inside struct declaration

[Rageking8]

Given the following code: link

struct Num {
    a: i32;
}

fn main() {
 
}

The current output is:

   Compiling playground v0.0.1 (/playground)
error: expected `,`, or `}`, found `;`
 --> src/main.rs:2:11
  |
2 |     a: i32;
  |           ^

error: could not compile `playground` due to previous error

Ideally the output should suggest replacing the ; with , since a suggestion already exist for an incorrect semicolon usage at the end of the struct declaration (after the closing brace).

[ChayimFriedman2]

@rustbot claim