Add JVM support for `unowned_dependency_behavior`

[stuhood]

Python implements an unowned_dependency_behavior flag, which when set to warning or error will report that the owners of particular import statements could not be located. These warnings almost always represent misconfigurations due to bad source roots, missing thirdparty artifacts, missing thirdparty package metadata, etc.

It would be very good to add something similar for the JVM.

[stuhood]

A challenge for adding this for the JVM is that we currently intentionally introduce some false-positive symbols, by looking potentially-relative symbols up in multiple scopes:

pants/src/python/pants/backend/scala/dependency_inference/scala_parser.py

Lines 102 to 108 in a43ad4e

	def fully_qualified_consumed_symbols(self) -> Iterator[str]:
	"""Consumed symbols qualified in various ways.
	This method _will_ introduce false-positives, because we will assume that the symbol could
	have been provided by any wildcard import in scope, as well as being declared in the current
	package.
	"""

To resolve that, we would likely need to adjust the implementation of fully_qualified_consumed_symbols for Java/Scala/Kotlin to instead yield sets of symbols, where only one "guess" in each set actually needed to match to avoid the warning. For example: the result of this test would instead be something like:

{
    {"io"},
    {"io.apply", "java.io.apply"},
    {"pio"},
    {"pio.apply", "org.pantsbuild.io.apply"},
    {"sio.apply", "scala.io.apply"},
    {"sio"},
}