O.Invert doesn't work for interfaces (just for types)

[regevbr]

🐞 Bug Report

Describe the bug

O.Invert doesn't work for interfaces (just for types)

Reproduce the bug

type O_INVERT = {
    A: 'Av';
};

type INVERT_O = {
    Av: 'A';
};

interface O_INVERT1 {
    A: 'Av';
}

interface INVERT1_O {
    Av: 'A';
}

checks([
    check<O.Invert<O_INVERT>, INVERT_O, Test.Pass>(), // PASSES
    check<O.Invert<O_INVERT1>, INVERT1_O, Test.Pass>(), // FAILS
])

Expected behavior

Both tests in the example should pass

Additional context

The reason for this issue is explained here:

Object types have an implicit index signature, but interfaces don't (for safety reasons), so they don't extend an index type.