Add a GitHub workflow to run the tests manually

[fabiobrz]

This is to add a GitHub workflow for allowing users to trigger tests against a given WildFly version, or the default which is configured via the project properties in the POM file.

• N.B.: the workflow runs on Linux based runners only ATM, since a "file name too long" exception pops up when executing the WildFly build on Windows.
• CI runs:

1. With custom Wildfly, regular execution
2. With custom WildFly, bootable execution
   
3. With default WildFly, regular execution
4. With default WildFly, bootable execution

The failure in the microprofile-fault-tolerance DatabaseCrashTest is unrelated

Resolves #311

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Please make sure your PR meets the following requirements:

• Pull Request contains a description of the changes
• Pull Request does not include fixes for multiple issues/topics
• Code is formatted, imports ordered, code compiles and tests are passing
• Link to the passing job is provided
• Code is self-descriptive and/or documented
• Description of the tests scenarios is included (see Update PR template to include TPG stuff #46)

[marekkopecky]

PR LGTM, merging, thank you!

[marekkopecky]

LGTM