Build the library using github actions and publish to maven central

[allanmoso]

This repo is currently not yet published to maven central. We would like to build this repo using GitHub actions and publish the artifact to maven central.

[allanmoso]

@dbirks There are some changes in PR #9 that added changes that allows us to publish to Maven Central approved repo (Sonatype). See https://github.com/egineering-llc/salesforce-oauth/blob/main/release.md

[allanmoso]

@dbirks I added the secrets for all of the environment variables described in this guide: https://github.com/actions/setup-java/blob/main/docs/advanced-usage.md#publishing-using-apache-maven

The secrets are named:
MAVEN_CENTRAL_TOKEN
MAVEN_GPG_PASSPHRASE
MAVEN_GPG_PRIVATE_KEY
MAVEN_USERNAME

[dbirks]

Cool! GPG too 🙂

I'll work on a PR to add that today or tomorrow.

And I'll have to play with it on my fork, but I may end up splitting up the mvn release command to do one commit at a time, and do a git push in between each step. That way there'll be multiple pushes, triggering multiple publishes.

Thank you, lots of new stuff to me, I'll take a look.

[dbirks]

Better late than never... opened #17 to run the mvn release command. Also making it manually-triggered only.