[DNM] [POC] Allow default parameters to be added to operator functions

[mininny]

This PR allows operator functions to have more than one or two parameters as long as they are default parameters, allowing something like :

infix operator <-
// Still infix because it has 2 formal arguments and 1 default
public func <- (lhs: T, rhs :T, file: StaticString = #file) -> U { /**/ }

This can be useful in scenarios when you want to pass some other parameters for other purposes like logging.

This PR changes the previous logic of checking the operator function's parameter count directly to only check the parameters that do not have default values.

This is an additive feature to the swift language and does not have backwards-breaking changes.

According to the original issue, this addition requires a swift evolution review, so this PR is for POC purposes. It still needs proper formatting and some code-level optimizations. 🙃

Resolves #54301