Enhancement to dynamically use test project for "no diagnostics" automated tests

[TrevCraw]

Description:

In https://github.com/eclipse/lsp4jakarta/pull/483, a new test project was added which includes fake Jakarta imports in order to test the scenario where we should only be providing diagnostics when the fully qualified Jakarta package name is available as an import.

Currently, this means that any updates made to the original test project will need to be made to the second project as well. In order to avoid dual maintenance, we could dynamically retrieve the Java files from the original test project (jakarta-sample) and then modify the imports to make them fake before passing them as input to the "no-diagnostics" test.