Prep v6 beta release

[nicolethoen]

### Tasks
- [x] Make sure all extensions are up to date with all changes on main branches
- [x] Identify beta release candidate
- [ ] https://github.com/patternfly/patternfly-org/issues/4116
- [ ] https://github.com/patternfly/patternfly-org/issues/4137
- [ ] Update all extensions to use beta release
- [ ] https://github.com/patternfly/patternfly-org/issues/4168
- [ ] Ensure codemods are complete
- [ ] Update testing template and let testers/products know beta candidates
- [ ] https://github.com/patternfly/patternfly-org/issues/3991

Now, post beta release, but immediately after:

### Tasks
- [ ]  Rename branches (v6 -> main, main -> v5)
- [ ] Update configs in all repos to stop releasing alphas and begin releasing prereleases
- [ ] Update configs in v5 branches to continue releasing v5