Release v0.79.0 (googleapis#4402)

Release google-cloud-java v0.78.0 (googleapis#4386)

Created enum Region.java to retrieve Regions without doing request. (g…

…oogleapis#4309)

Release v0.76.0 (googleapis#4298)

Release v0.75.0 (googleapis#4282)

Release v0.74.0 (googleapis#4222)

Release google-cloud-java v0.73.0 (googleapis#4191)

* Release v0.73.0

* Fix version replacements

* Move Spanner to GA section

* Fix doclint option

* Fix pom issues for Bigtable emulator

Release v0.72.0 (googleapis#4113)

Release v0.71.0 (googleapis#3978)

Release google-cloud-java v0.70.0 (googleapis#3921)