[lit-analyzer] no-missing-import should have the ability to ignore inferred type-only imports

[43081j]

Consider this code:

import {List} from '@material/mwc-list';

interface Foo {
  node: List;
}

// elsewhere...

class MyElement extends LitElement {
  render() {
    return html`<mwc-list></mwc-list>`;
  }
}

lit-analyzer will detect this as having imported mwc-list correctly.

though because we have imported and used only the type, it will be dropped once we transpile the code. This means mwc-list will never actually be imported or defined.

In #139 i fixed this partially in that we ignored type-only imports. This means the following change would work:

import type {List} from '@material/mwc-list';

In this case, lit-analyzer will detect we haven't actually imported mwc-list and will error.

Not everyone uses type-only imports, so it would be very helpful if we could do the same but for inferred type-only imports (i.e. infer that it is only used as a type and ignore it if so).