SDK / exoplayer

- Add proguard rules for libraries/extensions into .aar files
- Add proguard rules to retain CEA608/708 decoder constructors
- Remove lots of default config from gradle files
- Remove disabling of abort on lint error
- Enable optimizations on release builds of demo app

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=144350233