ci(gh-actions): add test strategy matrix

[erisu]

Motivation, Context & Description

This PR adds the test strategy matrix:

Android:

• 5.1 (API 22)
• 6 (API 23)
• 7 (API 24)
• 7.1 (API 25)
• 8 (API 26)
• 8.1 (API 27)
• 9 (API 28)
• 10 (API 29)
• 11 (API 30)

All tests uses Java 8 except for API 30. API >=30 will use Java 11.

iOS:

• 12.x
• 13.x
• 14.x

Starting April 26, 2021, all iOS and iPadOS apps submitted to the App Store must be built with Xcode 12 and the iOS 14 SDK.

Because of this requirement by Apple, we will only be testing against the latest Xcode release. We will be using the latest-stable flag which excludes beta.

Additionally, since iOS versioning is slightly different, when a new version is released, we will need to manually update the configuration files.

./conf/pr/local/ios-<VERSION>.config.json

For Plugin Repos:

In general, these workflow configs should be able to be copy to each plugin with no change required.

Testing

• iOS Tests: https://github.com/erisu/cordova-paramedic/actions/runs/1197731484
• Android Test: https://github.com/erisu/cordova-paramedic/actions/runs/1197731486
• Chrome Tests: https://github.com/erisu/cordova-paramedic/actions/runs/1197731485

Checklist

• [x] I've run the tests to see all new and existing tests pass
• [x] I added automated test coverage as appropriate for this change
• [x] Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• [x] If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)

[erisu]

IF we test @nightly we would have to think about what to cover. I believe it would also need to be on a separate workflow and separate PR.

We don't want nightly tests failures preventing PRs. Maybe run as a cron job and not related to PRs or pushes.

Then there are also nightly versions of Cordova-CLI, Cordova-Platforms, and also OS platforms.

At this time, I think it is not something we should consider. I am not against the idea but don't think it is related to this PR. For sure something to investigate after getting our plugins passing again.