This will remove some instances where we're using `as unknown as T` and
replace them by a call to `mockedObject<T>()`. The `mockedObject`
function is a bit more explicit about what it does and has types which
ensure that the methods that are set on the object actually exist.
Unfortunately, we can't fully get rid of `as unknown as T` in the
`mockedObject` function. However, this construct is more localized and
does not need to be used in as many places. If we do enable an ESLint
rule to prevent the use of `as unknown as T`, I would feel comfortable
with disabling the rule for the `mockedObject` function.
