fix: Fix inlining closures from local variables and functions

[rmehri01]

Previously, closures were not properly wrapped in parentheses for the inline_local_variable and inline_call assists, leading to the usages being incorrectly called:

fn main() {
    let $0f = || 2;
    let _ = f();
}

Now produces:

fn main() {
    let _ = (|| 2)();
}

Instead of:

fn main() {
    let _ = || 2();
}

Closes #15639

[lnicola]

Thanks!

@bors r+

[bors]

📌 Commit ea11846 has been approved by lnicola

It is now in the queue for this repository.

[bors]

⌛ Testing commit ea11846 with merge c22bb03...

[bors]

☀️ Test successful - checks-actions
Approved by: lnicola
Pushing c22bb03 to master...