Assorted updates - Githubissues

Description

Update gitignore to the latest Unity .gitignore from https://github.com/github/gitignore/blob/main/Unity.gitignore (while maintaining existing customizations)
Add MSFT copyright header to sample scripts
Minor formatting to sample scripts
Remove MR scoped registry from the project settings until we get confirmation that it's okay to use
- MRTK tarballs are already present in the repo, so there are no package issues
Turn off the deprecated MRTK service inspectors/facades to clean up the scene hierarchy
Update some MRTK profile settings to match the latest recommendations