Closes #55: Adds template to e2e tests

[Miraeld]

Description

Fixes #55

Documentation

User documentation

Technical documentation

Pages https://e2e.rocketlabsqa.ovh/ll_bg_css_double_colon/ & https://e2e.rocketlabsqa.ovh/ll_bg_css_single_colon/ have been created to ensure the test are running.

Type of change

• Enhancement (non-breaking change which improves an existing functionality).

[Mai-Saad]

@Miraeld Thanks for the PR. Please find notes below:
1- Two of the backstop-generated reports are empty (probably the ones related to single/double colon templates) => I checked backstop.json here and can't see any entry for the 2 new pages
2- The templates of single/double colon require hover on some elements, so we can either handle hover on test or see if we can update the template itself .. @jeawhanlee what do you think?

Update
1- works fine after updating the wp-config.ts file to match the sample file
2- we can discuss if we will need to handle the hover

[Mai-Saad]

• Updated double colon template to include the markup for :: and : without hover and it's working fine
• For the hover As a QA eng, I'd like to do VR tests on templates that needs specific action i.e hover #65