Use import type for imports in same folder

This CL is the result of applying the following regex:

```
import (.+) from '(.+)';\s+// eslint-disable-line no-unused-vars
```

and replace it with

```
import type $1 from '$2';
```

in all `*.ts` files. Some manual cleanups are performed when there
were imports that included both types and actual symbol references.

[email protected]

No-Presubmit: True
Bug: none
Change-Id: Ia520129af8518b7285c2691a15332a472515cfd3
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2720252
Commit-Queue: Tim van der Lippe <[email protected]>
Reviewed-by: Paul Lewis <[email protected]>
diff --git a/front_end/console/ConsoleViewMessage.ts b/front_end/console/ConsoleViewMessage.ts
index 768ca20..fa32aa5 100644
--- a/front_end/console/ConsoleViewMessage.ts
+++ b/front_end/console/ConsoleViewMessage.ts
@@ -46,7 +46,7 @@
 import * as ThemeSupport from '../theme_support/theme_support.js';
 import * as UI from '../ui/ui.js';
 
-import {ConsoleViewportElement} from './ConsoleViewport.js';  // eslint-disable-line no-unused-vars
+import type {ConsoleViewportElement} from './ConsoleViewport.js';
 
 export const UIStrings = {
   /**