Validate 90/10 of inference in test Java/Scala repositories

[stuhood]

I've spent some time validating inference in akka-http here: akka/akka-http@main...stuhood:stuhood/pants-v2-spike (commits useful to review independently), with the following results:

• 763 files compiling successfully
• 103 files failing to compile
  • Almost entirely in tests, so most issues have been exposed.

To get to this point, edits were made to BUILD files with the following frequency (and no relevant edits made to source files):

• 19 [jvm] Split thirdparty/firstparty packages need finer-grained thirdparty definitions #13661
• 5 Scala partially qualified symbol not inferred #13740
• 4 Nested package statements not inferred for Scala #13655
• 2 Scala symbols declared in package object end up in wrong scope #13753
• 2 Java imports of Scala symbols with trailing $ not inferred #13662
• 1 Annotations in Scala not extracted as consumed types #13751
• 1 Scala import of Java method not inferred #13750
• 1 Java public-static-final field type not declared as exported #13746
• 1 Java import of inner enum not inferred #13745
• 1 Scala wildcard import from empty package fails #13742
• 1 Java FQT with trailing method call not inferred #13741
• 1 Scala types not extract from lambdas in method signatures #13663
• 1 Add overrides to java/scala_sources and (scala_)junit_tests targets #13297

[stuhood]

Based on this, we're going to prioritize the top few issues, but otherwise call this complete.