move links from `osrf` repos to `open-rmf`

[codebot]

Many links remain in the text to the old osrf repos, such as osrf/rmf_demos. We need to work our way through the text and update the repos to their new home in the open-rmf GitHub organization.

[mdfesto]

@codebot I believe this can now be closed.

I've gone through and updated or submitted pull requests (for those I wasn't more confident on) for all links that I found either (1) pointing to osrf or (2) had a broken link