refactor ContentOuputStream to ContentPluginOutput ready for perfromance enhancements
copy  Reader from ContentPluginOutput to InputSource
performance: get CommonJsContentPlugin creating Reader rather than using OutputStream
performance: convert NamespacedJsContentPlugin to use Reader
performance: convert ThirdPartyContentPlugin to use Reader
performance: convert CSSContentPlugin to use Reader
performance: convert XMLContentPlugin to use Reader
performance: convert HTMLContentPlugin to use Reader
remove timer commands
Merge branch 'develop' into content-plugin-performance
Rewrite the `test` library to CommonJS style.

- rewrite all code under test/src to new CommonJS style
- update formating of the majority of the code (mostly whitespace)
- use `require()`s instead of namespaced references in tests
- also update the `viewhandler` tests to use `require()`s
Add ServiceRegistry tests

This tests have been (mostly) ported from the old BR code base. I've
cleaned them up a bit, removed the ones that are no longer valid and added
a couple of new ones.

This fixes #763
peformance: fix test failures caused by removing beuffering
Merge branch 'develop' into content-plugin-performance
memoizing xml bundler config
removing unused imports
removing the encoding header since it can be set via HTML
moving classes into subpackages
removing tests we dont need now asset encoding will be set using the <meta> tag
adding link to github workflow from readme