A class that is provided as Angular service is required to have an `@Injectable()` decorator so that the compiler generates its injectable definition for the runtime. Applications are automatically migrated using the "missing-injectable" schematic, however libraries built for older version of Angular may not yet satisfy this requirement. This commit ports the "missing-injectable" schematic to a migration that is ran when ngcc is processing a library. This ensures that any service that is provided from an NgModule or Directive/Component will have an `@Injectable()` decorator. PR Close #33362
Angular Compatibility Compiler (ngcc)
This compiler will convert node_modules compiled with ngc, into node_modules which
appear to have been compiled with ngtsc.
This conversion will allow such "legacy" packages to be used by the Ivy rendering engine.
Building
The project is built using Bazel:
yarn bazel build //packages/compiler-cli/ngcc
Unit Testing
The unit tests are built and run using Bazel:
yarn bazel test //packages/compiler-cli/ngcc/test
Integration Testing
There are tests that check the behavior of the overall executable:
yarn bazel test //packages/compiler-cli/ngcc/test:integration