Add import type shorthand syntax

[jeffmo]

Currently, importing both types and values from the same modules requires two statements with most of the same boilerplate in both statements:

import {someValue} from "blah";
import type {someType} from "blah";
import typeof {someOtherValue} from "blah";

This gets tediously repetitive and adds a lot of boilerplate to JS files.

This PR implements a proposal from @leebyron to add an additional type/typeof shorthand to vanilla-import statements for individual named specifiers so that the above code can be written more concisely as:

import {
  someValue,
  type someType,
  typeof someOtherValue,
} from "blah";

This PR does not remove import type or import typeof statements -- it only adds the shorthand to vanilla import statements.

Note also that I've banned usage of the shorthand with import type and import typeof statements since the need for shorthand in those is far less common and often combinatorially confusing:

import type { type T } from "foo"; // <-- parse error
import typeof { type T } from "foo"; // <-- parse error

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[CodyReichert]

Nothing super constructive, but I'm really looking forward to this. Nice work!

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