Feature/more updates

[guzmandrade-dev]

Closes https://github.com/WebDevStudios/wds-block-based-theme/issues/5

DESCRIPTION

• Updated theme.json to version 2 following https://schemas.wp.org/trunk/theme.json and https://developer.wordpress.org/block-editor/reference-guides/theme-json-reference/theme-json-migrations/
• Added templates for the posts archive and a new two-column structure to position the sidebar on the right.

SCREENSHOTS

OTHER

• [ ] Is this issue accessible? (Section 508/WCAG 2.0AA)
• [X] Does this issue pass all the linting? (PHPCS, ESLint, SassLint)
• [ ] Does this pass CBT?

STEPS TO VERIFY

How do we test this?

The theme still works, and styles on theme.json are now functional.

DOCUMENTATION

Will this pull request require updating the theme documentation? Currently on README.md.