Introduces a new migration schematic for adding the "@Injectable()"
decorator to provider classes which are currently not migrated. Previously
in ViewEngine, classes which are declared as providers sometimes don't
require the "@Injectable()" decorator
(e.g. https://stackblitz.com/edit/angular-hpo7gw)
With Ivy, provider classes need to be explicitly decorated with
the "@Injectable()" decorator if they are declared as providers
of a given module. This commit introduces a migration schematic
which automatically adds the explicit decorator to places where
the decorator is currently missing.
The migration logic is designed in a CLI devkit and TSlint agnostic
way so that we can also have this migration run as part of a public
CLI migration w/ `ng update`. This will be handled as part of a follow-up to reiterate on console output etc.
Resolves FW-1371
PR Close#30956
Paul Gschwendtner