Migrate CI to Github Actions

[ChristianMurphy]

AppVeyor and Travis CI to not be enabled for uPortal-project/uportal-home (in the most recent commit, only GitHub pages appears to be running 97b3da5).
And even if Travis was running, it has lowered build time limits for open source projects https://jamescooke.info/travis-hitting-githubs-api-limits-for-open-source-projects.html
It may be worth migrating to GitHub actions, as some of the other uPortal-project repos have.

Some relevant starters, https://github.com/uPortal-Project/JasigWidgetPortlets/blob/211faf438f65637a7ba97f93764c7f4bbc488ac2/.github/workflows/CI.yml#L1-L29 gives an example of testing Maven and Java, https://github.com/uPortal-Project/uPortal-web-components/blob/7c37a17c995121a3627fbe353f733b45dcecf5ff/.github/workflows/CI.yml#L1-L35 gives an example with Node and NPM.

Happy to help if there is interest in migrating.