Remove all direct uses of SkyframeExecutor.reporter.

Instead, pass an appropriate EventHandler instance in. This is in preparation
for creating a per-command EventHandler, in preparation for allowing multiple
commands to run in parallel. This is removal of shared global state.

--
MOS_MIGRATED_REVID=103828963
diff --git a/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java b/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
index ea1604a..e9d7369 100644
--- a/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
+++ b/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
@@ -436,6 +436,7 @@
       Profiler.instance().markPhase(ProfilePhase.EXECUTE);
 
       builder.buildArtifacts(
+          env.getReporter(),
           additionalArtifacts,
           analysisResult.getParallelTests(),
           analysisResult.getExclusiveTests(),