Add Trix editor to Product Description Editor

[lin-d-hop]

Description

Replace the existing angular WYSIWYG editor with the Trix editor.
Here https://openfoodnetwork.org.uk/admin/products/new
And here https://openfoodnetwork.org.uk/admin/products/[_product-name_]/edit

Acceptance Criteria & Tests

1. Remove old angular WYSIWYG
2. Replace with the Trix editor for product description
3. Test <hr> and <br>. Plus bullet points, strikethrough, headings etc etc.

From: openfoodfoundation/wishlist#427

[RachL]

@lin-d-hop @jibees does this close openfoodfoundation/wishlist#63 ?

[jibees]

As far as I know: no ; trixeditor doesn't allow to insert HTML content.

[RachL]

@jibees have you check the last comment of the issue? openfoodfoundation/wishlist#63 (comment)

Also hr and br are html right? :p

[jibees]

I think I don't understand sorry.

Trixeditor can be tested here: https://trix-editor.org/ (or by staging the PR)

[RachL]

@jibees the 3rd accetpance criteria here says

Test <hr> and <br>

[jibees]

I missed that, you're right. Back in In dev since this still needs to implements horizontal rule, ie. <hr />(<br />is break in text or carriage-return and is simply implemented via an Enter character)