feat: Expose Python/Groovy version to clients

[devinrsmith]

• Sets groovy.version configuration property, as sourced from class groovy.lang.GroovyShell.
• Sets python.version configuration property, as sourced from python code platform.python_version()
• Adds groovy.version and python.version to client.configuration.list in dh-defaults.prop (to be returned to client as part of ConfigService.GetConfigurationConstants gRPC)
• Adds io.deephaven.client.examples.PrintConfigurationConstants to invoke and print out results of ConfigService.GetConfigurationConstants

Fixes #5938

[devinrsmith]

Here's the output:

file.separator=/
barrage.version=0.6.0
http.session.durationMs=300000
web.webgl.editable=true
web.storage.layout.directory=/layouts
java.version=21.0.4
deephaven.version=0.37.0-SNAPSHOT
groovy.version=3.0.22
web.webgl=true
python.version=3.12.4
web.storage.notebook.directory=/notebooks

[niloc132]

Keep in mind two assumptions this imposes:

• ConfigService must always initialize before any PythonDeephavenSession I'm mistaken, this isn't required
• Exactly one PythonDeephavenSession (no chance of multiple sessions with potentially different versions)

[devinrsmith]

ConfigService must always initialize before any PythonDeephavenSession

I don't think this is correct. io.deephaven.server.config.ConfigServiceGrpcImpl#getConfigurationConstants checks Configuration at runtime, not construction time. The construction time is only to prime the class-based versions.