Allow periods (and many other ASCII characters) in branch names

[arielshaqed]

I would like to name branch some-test.ariels. But we only allow branches matching /^\w[-\w]*$. I understand these limitations:

• Repo names must match S3 bucket names or host-style addressing will not work.
• Branch names cannot contain slashes or lakefs://repo/branch/key will not work.

Neither of these explain why I cannot have a period . in a branch name.