This changes all our dependencies to use the 3.0-style dep types (api and implementation). Generally it just makes everything api unless known otherwise, but moving to implementation where possible in the future would be desirable.
PiperOrigin-RevId: 177391618
This also bumps up the build tools + Android gradle plugin version, since these
were out of date, and removes a couple unused version values.
PiperOrigin-RevId: 153652782
This new structure will allow for a top-level gradle file and a multi-project
build (which is a more typical structure for things). In the future, it will
allow us to place other projects in here as well (such as sample applications).
PiperOrigin-RevId: 141247594
