Add suggestion to errors about @Inject on inner classes
Add suggestion to errors about @Inject on inner classes

Fixes https://github.com/google/dagger/issues/1109

RELNOTES=n/a

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189962031

cgruber/dagger,ze-pequeno/dagger,cgruber/dagger,cgruber/dagger,google/dagger,google/dagger,google/dagger,ze-pequeno/dagger,ze-pequeno/dagger,ze-pequeno/dagger,dushmis/dagger,google/dagger,dushmis/dagger