Fixing UTF-8 tests, CompositeJsContentPlugin was not setting the outputStreamWriter encoding when creating the writer
- Updated CssContentPlugin to use brjs defaultOutputEncoding
- Updated App so that it too uses defaultOutputEncoding, but so that it's passed in the writer by BRJSServletFilter
- Paired with @dchambers
- Removed other unused imports
Adding library manifest css test
Merge branch 'bundler-exploration' into sdk-lib-restructure

Conflicts:
	brjs-core/src/main/java/org/bladerunnerjs/model/App.java