fix: bun1338 Add BigCommerce Requirements for store logos added in B2BE

[BrianJiang2021]

Jira: BUN-1338

What/Why?

Issue: The Buyer Portal seems to be cropping the logo. It doesn’t look very good. We should adjust to fix most logo dimensions

desk: 200x65 px mob: 140x40 px

Rollout/Rollback

undo pr

Testing

desk:

mob: