* Formatting follow-up
- Adds formatting commits to .git-blame-ignore-revs so that they don't
distract during Git blame
- Restores hard line breaks in Troubleshooting.md using `\` instead of
trailing spaces
- Changes formatting of some string literals and comments
- Fixes accidental Javadoc and comment issues introduced by manual changes
of formatting commit
- Fixes license header in $Gson$Types.java erroneously being a Javadoc
comment and being reformatted
- Slightly changes `JsonReader` `getPath` and `getPreviousPath` documentation
to help Javadoc detect first sentence as summary
* Remove `spotless:off` markers
* Add empty line before comment
* Check format for .github YAML files