Update Kotlin roadmap (#5397)

* first draft

* align with doc

* remove Stabilize ES2020 target

* Danil review

* Added KT links where missing; replaced OSIP and empty links with relevant ones for the Done items, where KT never existed before.

* put tip back

* move wasm together

* Aleksey review

* change default warnings/errors to in progress

* last review

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Co-authored-by: Sarah Haggarty <sarahhaggarty@users.noreply.github.com>
Co-authored-by: Evgenii Pavelev <evgenii.pavelev@jetbrains.com>

Author: sarahhaggarty