Duplicated sub-conditions in boolean expression lint

What it does

In this code below the test contains two repeated expressions. This could be a mistake (a bug) so I think it's a good idea for Clippy to spot it with a lint similar to "ifs_same_cond".

Lint Name

redundant_sub_cond

Category

suspicious

Advantage

No response

Drawbacks

No response

Example

fn test1(s: &str) -> bool {
    if s.is_empty() || s.is_empty() {
        return false;
    }
    true
}

Start by comparing the proposed redundant_sub_cond lint with the existing ifs_same_cond lint mentioned in the issue, then locate Clippy's lint implementation and test conventions. Add coverage for the repeated s.is_empty() expressions shown in the example, with completion demonstrated by the lint detecting that duplicated sub-condition.