less twitter

[maelle]

Fix #590

• Remove link to Twitter account from the footer. (is this the right choice?)
• Remove button to share on Twitter from the sidebar of posts, job postings, comm calls. (is this the right choice?)
• New posts will use the "social" metadata, for old ones the templates will still pick up the "twitter" metadata. I have checked the preview on Twitter/Mastodon and Slack for the Qualtrics & cite packages post I edited but would appreciate a second pair of eyes. https://deploy-preview-592--ropensci.netlify.app/blog/2022/08/09/working-with-qualtrics-data-excluding/ + https://deploy-preview-592--ropensci.netlify.app/blog/2021/11/16/how-to-cite-r-and-r-packages/

[yabellini]

I checked your changes and I think is consistent with our message. +1 to the changes.
I check the deploys of the blog posts you linked in your comment. No Twitter on the sight, any other thing you want we check?

[maelle]

merged but feedback still welcome if you find something amiss / suboptimal later on @yabellini @steffilazerte