Intelligently create valid git branch names

[valtism]

When creating a branch by opening git: branch and typing a new name, if an invalid name is used: e.g. feature/hello world it will fail with the error:

the given reference name 'refs/heads/feature/hello world' is not valid; class=Reference (4); code=InvalidSpec (-12)

In VS Code, if you enter something like feature/hello world it will intelligently replace the spaces with dashes, giving you the name feature/hello-world

It would be a nice quality of life improvement for zed to adopt something similar