add a constraint for immutable types

say, i have a generic function that by design requires that its parameters may only take immutable arguments, i wish i could get such guarantee from TS by declaring my function as follows:

function doThings<readonly T>(value: T): Result<T> {
   // ...
}

as far as how to make an interface immutable:

readonly interface Point {
   readonly x: number;
   readonly y: number;
}

so the problem being solve here is to make sure that the caller won't mutate the argument after it is passed to the function

simple use case: a hash-based data container, which calculates a hash of a given value, and will store it at that hash, and it all will work until the value is mutated outside and tha stored hash is no longer valid, so the container doesn't really work anymore

another use case: a cache or object pool or any other situation when there are many parties involved in taking hold of the same object, which must be guaranteed from being mutated by one party to prevent spooky action at a distance for all other parties

In der Issue werden keine Quelldatei, kein Test und kein Einstiegspunkt genannt. Beginne damit zu prüfen, wie TypeScript generische Einschränkungen und readonly-Typen darstellt; die Arbeit ist abgeschlossen, wenn die vorgeschlagene Garantie für unveränderliche Argumente eine abgestimmte Semantik, eine Abdeckung der Implementierung und Tests für die genannten Fälle von Hashing, Caching und Objektteilung hat.