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
This commit uses the correct property name (`prettier` vs `pretter`) to
check whether prettier is enabled via the config.
(It also fixes some typos in `dev-infra`.)
PR Close#41860
Joey Perrott