win: unify registry setting as TrustedInstaller

- Introduce SetRegistryValueAsTrustedInstaller function to unify setting
  registry values as TrustedInstaller.
- Introduce RunPowerShellWithMinimumWindowsVersion function to unify
  Windows version specific registry modifications.
- Add more documentation for scripts using TrustedInstaller.
- Correct revert code for affected scripts to match default OS behavior
  (setting registry value back) instead of just deleting keys.