Implement `BinaryToDecimal` which takes an exact string type `S` consisting 0 and 1 and returns an exact number type corresponding with `S` when `S` is regarded as a binary.
You can assume that the length of `S` is equal to or less than 8 and `S` is not empty.
```ts
type Res1 = BinaryToDecimal<'10'>; // expected to be 2
type Res2 = BinaryToDecimal<'0011'>; // expected to be 3
```