Add integration test for tycho-apitools-plugin:verify mojo

[HannesWell]

This adds an integration test for the tycho-apitools-plugin:verify mojo.

On my Windows computer this currently fails saying that the baseline must not be null.
Furthermore I currently have no good idea how encode the repository URL as a relative path. At the moment I use file:///${maven.multiModuleProjectDirectory}/repositories/api-tools, but that fails on Windows since it mixes forward and backward slashes. But it should succeed on Unix.
Besides that the test-case needs some assertions.

FYI @laeubi.

[github-actions]

Test Results

0 files   -    543  0 suites   - 543   0s ⏱️ - 4h 8m 39s
0 tests  -    339  0 ✔️  - 322  0 💤  - 10  0 ❌  - 5 
0 runs   - 1 017  0 ✔️  - 979  0 💤  - 31  0 ❌  - 5 

Results for commit bcf182e. ± Comparison against base commit 9c423ce.

♻️ This comment has been updated with latest results.

[laeubi]

Furthermore I currently have no good idea how encode the repository URL as a relative path

The usual approach in the Itest is to have a variable (e.g. ${baselineRepo}) in the pom, then set this in the verifier via

File repo = new File(verifier.getBaseDir(), "..some path...");
verifier.setCliArgument("-DbaselineRepo"+=repo.getAbsoloutePath())

[laeubi]

@HannesWell this seem to break the generate test-case with:

.api_description not found

is a change in this area expected / intended? I currently can't see why this would interact here....

[HannesWell]

@HannesWell this seem to break the generate test-case with:

.api_description not found

is a change in this area expected / intended? I currently can't see why this would interact here....

No that was accidental. Thank you for fixing this in #2282.

Btw. if you want you can also push extra commits directly to my branch do avoid the need for an extra PR. :)