Add new compiler errors and flags when JVM compiles against JVM IR

From now on, the old JVM backend will report an error by default when
compiling against class files produced by the JVM IR backend. This is
needed because we're not yet sure that the ABI generated by JVM IR is
fully correct and do not want to land in a 2-dimensional compatibility
situation where we'll need to consider twice more scenarios when
introducing any breaking change in the language. This is generally OK
since the JVM IR backend is still going to be experimental in 1.4.

However, for purposes of users which _do_ need to compile something with
the old backend against JVM IR, we provide two new compiler flags:
* -Xallow-jvm-ir-dependencies -- allows to suppress the error when
  compiling with the old backend against JVM IR.
* -Xir-binary-with-stable-api -- allows to mark the generated binaries
  as stable, when compiling anything with JVM IR, so that dependent
  modules will compile even with the old backend automatically. In this
  case, the author usually does not care for the generated ABI, or s/he
  ensures that it's consistent with the one expected by the old compiler
  with some external tools.

Internally, this is implemented by storing two new flags in
kotlin.Metadata: one tells if the class file was compiled with the JVM
IR, and another tells if the class file is stable (in case it's compiled
with JVM IR). Implementation is similar to the diagnostic reported by
the pre-release dependency checker.

compiler/testData/cli/jvm/extraHelp.out

@@ -2,6 +2,7 @@ Usage: kotlinc-jvm <options> <source files>
 where advanced options include:
   -Xadd-modules=<module[,]>  Root modules to resolve in addition to the initial modules,
                              or all modules on the module path if <module> is ALL-MODULE-PATH
+  -Xallow-jvm-ir-dependencies When not using the IR backend, do not report errors on those classes in dependencies, which were compiled by the IR backend
   -Xallow-no-source-files    Allow no source files
   -Xassertions={always-enable|always-disable|jvm|legacy}
                              Assert calls behaviour
@@ -22,6 +23,8 @@ where advanced options include:
   -Xfriend-paths=<path>      Paths to output directories for friend modules (whose internals should be visible)
   -Xmultifile-parts-inherit  Compile multifile classes as a hierarchy of parts and facade
   -Xir-check-local-names     Check that names of local classes and anonymous objects are the same in the IR backend as in the old backend
+  -Xir-binary-with-stable-abi When using the IR backend, produce binaries which can be read by non-IR backend.
+                             The author is responsible for verifying that the resulting binaries do indeed have the correct ABI
   -Xmodule-path=<path>       Paths where to find Java 9+ modules
   -Xjava-package-prefix      Package prefix for Java files
   -Xjava-source-roots=<path> Paths to directories with Java source files