Add wrap suggestions for record variants

[WaffleLapkin]

This PR adds a suggestions to wrap an expression in a record struct/variant when encountering mismatched types, similarly to a suggestion to wrap expression in a tuple struct that was added before.

An example:

struct B {
    f: u8,
}

enum E {
    A(u32),
    B { f: u8 },
}

fn main() {
    let _: B = 1;
    let _: E = 1;
}

error[E0308]: mismatched types
  --> ./t.rs:11:16
   |
11 |     let _: B = 1;
   |            -   ^ expected struct `B`, found integer
   |            |
   |            expected due to this
   |
help: try wrapping the expression in `B`
   |
11 |     let _: B = B { f: 1 };
   |                ++++++   +

error[E0308]: mismatched types
  --> ./t.rs:12:16
   |
12 |     let _: E = 1;
   |            -   ^ expected enum `E`, found integer
   |            |
   |            expected due to this
   |
help: try wrapping the expression in a variant of `E`
   |
12 |     let _: E = E::A(1);
   |                +++++ +
12 |     let _: E = E::B { f: 1 };
   |                +++++++++   +

r? @compiler-errors

[compiler-errors]

Looks great ✨

@bors r+

[bors]

📌 Commit 1c2ea78 has been approved by compiler-errors

It is now in the queue for this repository.