Add import statement as 'import type' for types and interfaces (typescript)

[Treverix]

We can let intellij add a missing import and that also works on svelte source files with lang="ts".

The only trouble is: svelte requires that all types and interfaces to be imported as type

import type {SuiteSelectorEvents} from "./types";

while the current plugin adds it like that:

import {SuiteSelectorEvents} from "./types";

That is probably the default behavior of IDEA but it would be great if the plugin could add the import as import type here because otherwise we observe (pretty misleading) compile errors when we miss to fix it immediately.

[SelcukKayahan]

Same here. Already tried this among others: https://youtrack.jetbrains.com/issue/WEB-43269

[tomblachut]

Will be supported in 2021.2 as part of https://youtrack.jetbrains.com/issue/WEB-50851