In combination with the TS `noImplicitOverride` compatibility changes,
we also want to follow the best-practice of adding `override` to
members which are implemented as part of abstract classes. This
commit fixes all instances which will be flagged as part of the
custom `no-implicit-override-abstract` TSLint rule.
PR Close#42512
Rather than running ng-dev via ts-node, going forward ng-dev is generated and run
locally via node. Additionally, the generated file is tested on each commit to
ensure that the local generated version stays up to date.
PR Close#39089