Rule Request: Optional Property Write

This is a rule request. I'm willing to implement this myself and send a PR, but before doing that I'd like to know if the rule is wanted or not. To explain the desired rule, I'd like to first post the custom rule we are already using in our projects:

optional_property_write:
    included: ".*.swift"
    regex: '\S+!\.\S+\s*=[^=]\s*'
    name: "Writing Properties on Optionals"
    message: "Don't use ! to write into properties on optionals – use ? instead."
    severity: warning

I felt like this rule might be useful for other projects as well, which is why I'm posting it. What do you think about it? For us it helps a lot to prevent common issues and enforce a shared style.

Rationale

When assigning a value to a property of a type, some people used the ! syntax which will lead to a crash. In nearly all cases it is better to use ? instead to ensure the app doesn't crash due to this single property assignment. In cases where the existence of the variable is required, the if let or guard let syntax should be used anyways.

A few examples:

let label: UILabel?

// ❌ not acceptable
label!.text = "someString"

// ✅ acceptable
label?.text = "someString"

Start by reviewing the custom optional_property_write YAML rule and the Swift examples in the issue, then read the existing discussion for the maintainers' decision. Done means the project has decided whether to accept this rule; implementation scope and tests are not specified here.