Add compiler option to require explicit casts from any to other types

TypeScript Version: typescript@2.8.0-dev.20180320

Search Terms: explicit any conversion

Code

function x(): any {
	return 42
}

const y: string = x()

Expected behavior: I can use a compiler option to require an explicit cast from any to string, and the code above would give an error with that option enabled. Function x in the example usually comes from a library definition file like: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/9f4c75126167d0d8af759f58405d53d983e94ad0/types/yargs/index.d.ts#L226

Actual behavior: There is no such option.

Playground Link: http://www.typescriptlang.org/play/index.html#src=function%20x()%3A%20any%20%7B%0D%0A%20%20%20%20return%2042%0D%0A%7D%0D%0A%0D%0Aconst%20y%3A%20string%20%3D%20x()

Related Issues: #22464 (comment)

Provide feedback