[e.cash] Add blog page

Summary:
Adding the main blog page to the site

• use the getBlogPosts function from the last diff to getStaticProps for all of the posts
• render them on the page in a series of cards

note the theme color change is for this diff. That value worked better here and for the other places its used

Test Plan:
preview the site and see if everything looks good
npm run test

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: bytesofman, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14157