PROD-1562: Detect whether to resize images from the viewport meta tag

The way we calculate the dimensions for resizing images does not work for non-responsive websites. Disable resizing for websites that are not responsive (that don't have an ideal viewport meta tag).

Status: **Opened for review**

Reviewers: @jansepar 
JIRA: **https://mobify.atlassian.net/browse/PROD-1562**

## Changes
- Adds a `resize` option to Image Resizer that serves images through the IR backend without resizing them
- Auto detects whether to resize images based on the document's viewport meta tag

## How to test-drive this PR
- Run the tests and examples