Fix resource priority under name collision

[tanishiking]

Description

This PR adds a failing test for #1455

@liucijus mentioned this issue occurs around here https://github.com/bazelbuild/rules_scala/blob/master/src/java/io/bazel/rulesscala/scalac/ScalacWorker.java#L65-L71 but re-ordering those lines doesn't work (I guess because re-ordering them control the priority of resource, resource_jars, and classpath_resources. It's not about resource name crash with things in JAR files).

My hunch is this is caused because the executable file has a "wrong" order of CLASSPATH.
For example, bazel-bin/test/src/main/scala/scalarules/test/duplicated_resources/child/child (generated by$ bazel build //test/src/main/scala/scalarules/test/duplicated_resources/child) contains the following CLASSPATH order.
(see the definition of the target "child" here )

CLASSPATH="
  ${RUNPATH}test/src/main/scala/scalarules/test/duplicated_resources/parent/parent.jar:
  ${RUNPATH}../io_bazel_rules_scala_scala_library/scala-library-2.12.14.jar:
  ...
  ${RUNPATH}../bazel_tools/tools/java/runfiles/librunfiles.jar
  ${RUNPATH}test/src/main/scala/scalarules/test/duplicated_resources/child/child.jar:
  "

parent.jar is first, and child.jar is last.

I think we can fix this by moving child.jar to the first of CLASSPATH is the fix. Actually, moving child.jar to the place before parent.jar fixed the issue.

What do you think?

Motivation

see #1455

[liucijus]

@tanishiking indeed you're right, this is runtime behavior. I would look for problem in collect jars phase.

[tanishiking]

It looks like the problem is around here in phase_compile

rjars = depset(out.full_jars, transitive = [rjars]),

where out.full_jars is child.jar and rjars contains the rest of dependent jars.
I confirmed depset(out.full_jars, transitive = [rjars], order = "preorder|topological") fixes the issue, but I'm not really sure which order should we use. https://bazel.build/rules/lib/depset
(while topological-sort sounds safer than pre-topological-sort).
Turned out topological doesn't guarantee left-to-right between deps in BUILD and CLASSPATH. As a result of this, the test_multi_service_manifest in test_misc.sh failed because the order of service_manifest.txt reversed.
https://github.com/tanishiking/rules_scala/blob/447dec21affb414c1be18e1735b357b2a6e6c671/test/example_jars/expected_service_manifest.txt#L3

To guarantee the left-to-right order, changed the order to preorder

[liucijus]

Thanks, @tanishiking!

[tanishiking]

(Just force-pushed the change on test description) https://github.com/bazelbuild/rules_scala/pull/1456/files#diff-96060316d4c081f3a4d50a995f83805f403e50c478da6c2bd14c26068f84666cR7

[simuons]

Thanks @tanishiking