Get mail service to facilitate sending out correspondence on behalf of BIDS

[yarikoptic]

and to associate with the main domain, so we could

• get group emails to email corresponding groups like steering-group@bids-standard.org (bids.steering@gmail.com managed by @cmaumet ATM; or bids.maintainers@gmail.com managed by ...?)
• send emails as coming from BIDS address(es)

attn @bendhouseart to potentially further tune this up

[bendhouseart]

We should probably just use FastMail and add two users under the business plan ($5 per user per month) or use the personal duo plan for $8 per month.

I did just price a google workspace to make for an easy transition, but I'd rather move away from google than commit to a workspace just for email.

pinging @nellh to weigh in.