Flacoco crashes when a test method name contains spaces

Some JVM languages (e.g., Kotlin) allow [method names to contain spaces](https://kotlinlang.org/docs/coding-conventions.html#names-for-test-methods). This convention is used in many projects, such as lettuce-core, which is a subject in the APR-Comp. It has [a test method](https://github.com/lettuce-io/lettuce-core/blob/main/src/test/kotlin/io/lettuce/core/ScanFlowIntegrationTests.kt#L50) that looks like this:

```kotlin
@Test
fun `should scan iteratively`() = runBlocking {
...
}
```

Flacoco will crash on such projects because it won't escape the spaces.

I forgot the exact error because I encountered this bug a few months ago and now I don't have a Kotlin environment at hand, but I still remember what's going on in the code:
1. Flacoco calls the `runOnlineCoveredTestResultPerTestMethods` method in test-runner with a list of collected test method names [(code)](https://github.com/ASSERT-KTH/flacoco/blob/master/src/main/java/fr/spoonlabs/flacoco/core/coverage/framework/JUnit4Strategy.java#L25).
2. `runOnlineCoveredTestResultPerTestMethods` will then concatenate all test method names with a space [(code)](https://github.com/STAMP-project/test-runner/blob/463c821c7d5d9ab947ccd24d6dd0c8a7fda7f1ec/src/main/java/eu/stamp_project/testrunner/EntryPoint.java#L718),
3. ... and then transform it into a command-line argument and call `runGivenCommandLine` [(code)](https://github.com/STAMP-project/test-runner/blob/463c821c7d5d9ab947ccd24d6dd0c8a7fda7f1ec/src/main/java/eu/stamp_project/testrunner/EntryPoint.java#L729).
4. `runGivenCommandLine` will then spawn a new Java process with the given argument [(code)](https://github.com/STAMP-project/test-runner/blob/463c821c7d5d9ab947ccd24d6dd0c8a7fda7f1ec/src/main/java/eu/stamp_project/testrunner/EntryPoint.java#L820).

Therefore, if a test method name contains a space, it will be parsed as two arguments, crashing the command-line parser.

Maybe you can reproduce this issue and forward it to test-runner if necessary. Thanks again for your great project!

Start in flacoco's JUnit4Strategy.java at runOnlineCoveredTestResultPerTestMethods, then trace the referenced test-runner EntryPoint.java methods runOnlineCoveredTestResultPerTestMethods and runGivenCommandLine. Reproduce with a Kotlin test method containing spaces, and verify that the test-runner receives the method name as one test identifier rather than split command-line arguments.

Written by the indexing model from the issue text.