Add native `img` to the AMP validator

## Add native `img` tag to the AMP Validator

This issue falls under the umbrella of changes which are a part of the '`amp-img` deprecation': #30442.

We will be adding the native `img` tag to the validator which will allow for native `img` tags which require the following attributes...

Standard image:

- `alt`
- `decoding=async`
- `height`
- `loading=lazy`
- `src`
- `width`

Hero image:

- `alt`
- `data-hero`
- `decoding=async`
- `height`
- `src`
- `width`

Image using `srcset`:

- `alt`
- `decoding=async`
- `height`
- `loading=lazy`
- `sizes`
- `srcset`
- `width`

## Describe alternatives you've considered

These guidelines are fairly strict, we had considered having looser more granular validation rules for images trying to replicate specific amp-layout considerations, however for ease of development and for user understanding we have decided to start with more strict validation rules and allow for loosening of these restrictions in the future.

## Additional context

For additional documents see this document about [`amp-img` deprecation](https://docs.google.com/document/d/1tLqmz3g0a8PCOWwsQuPZ3Sx0MuqL8ly78I7eA-xOj-Q/edit?usp=sharing), and this document about [allowing native `img`](https://docs.google.com/document/d/135fsDOw-OfVNZbqr-aOY3ZVNKTzwCLcf8z6Dang2ygY/edit?usp=sharing) in valid amp documents.