Manually parenthesize tuple expr in `B014` autofix (#6415)
## Summary
Manually add the parentheses around tuple expressions for the autofix in
`B014`.
This is also done in various other autofixes as well such as for
[`RUF005`](https://github.com/astral-sh/ruff/blob/6df5ab40987cba7bb5681c2445caaf83ebcfbf7d/crates/ruff/src/rules/ruff/rules/collection_literal_concatenation.rs#L183-L184),
[`UP024`](https://github.com/astral-sh/ruff/blob/6df5ab40987cba7bb5681c2445caaf83ebcfbf7d/crates/ruff/src/rules/pyupgrade/rules/os_error_alias.rs#L137-L137).
### Alternate Solution
An alternate solution would be to fix this in the `Generator` itself by
checking
if the tuple expression needs to be generated at the top-level or not.
If so,
then always add the parentheses.
```rust
} else if level == 0 {
// Top-level tuples are always parenthesized.
self.p("(");
let mut first = true;
for elt in elts {
self.p_delim(&mut first, ", ");
self.unparse_expr(elt, precedence::COMMA);
}
self.p_if(elts.len() == 1, ",");
self.p(")");
```
## Test Plan
Add a regression test for this case in `B014`.
fixes: #6412
