Add generation of managed model element implementations

+review REVIEW-5226
Move files to follow package naming convention.
fix unknown os ci build

+review REVIEW-5228
Add assert matching to current wording.
Improving documentation examples and ensuring that all are integration testing.

+review REVIEW-5202
Bump the font sizes for the docs.
minor formatting.
release notes polishing.
release notes polishing.
Add TextResource to the DSL ref.
release notes polishing.
Bump some more fonts.
No promoted features :(
release notes polishing.
Break long line.
release notes polishing.
release notes polishing.
release notes polishing.
No deprecations in this release.
release notes polishing.