Add a mechanism to check if a late variable is initialised

[hrajwade96]

At present there is no way to check if a late variable is actually initialised or not,
Can we add a way to check this?
for example in Kotlin we can check if a lateinit variable is initialised :
Kotlin lateinit variables

If someone can point to where this code needs to be modified I can also work on this PR.

[julemand101]

Sounds like a duplicate of: #1028

[mateusfccp]

Sounds like a duplicate of: #1028

This one is closed, I think #3680 is equivalent and is still open.

[lrhn]

I think #1028 is the best fit (and it being closed is a big hint that this is an unlikely feature to happen, at least by itself).

The #3680 does include a ?? operator for late variables, but I'd not expect that operator to be added alone, only if it's part of the change that also adds late parameters. For late variables, you're expected to know whether they're initialized.

But definitely a duplicate of one or the other.