WIP: Minor inconsistencies discovered during the smithy migration

[agluszak]

• Sometimes we use a map for passing environment variables (https://build-server-protocol.github.io/docs/extensions/jvm#test-environment-request), sometimes we use a list (https://build-server-protocol.github.io/docs/extensions/scala#scala-specific-data-kinds-for-debugging)
• JVM environment requests include an originId. Why?
• Scala test classes request also has an originId (both in params and respons)
• framework field in ScalaTestClassesItem is marked as optional, but with an annotation "It's optional in order to maintain compatibility, however it is expected from the newer implementations to not leave that field unspecified.". Let's make it obligatory then.
• buildTarget/inverseSources in should be called textDocument/inverseSources
• split TaskData into TaskStartData, TaskProgressData and TaskFinishData
• a field is called className in ScalaTestSuiteSelection while the same field is serialized to class in ScalaMainClass

[agluszak]

Related: #562