Lang.JVM.Codebase: experimental support for loading JIMAGE files

[RyanGlScott]

This allows crucible-jvm to deal with JDK 9 or later, which packages its standard library not in a JAR file, but in a JIMAGE file. Extracting .class files from JIMAGE files proves to be surprisingly tricky, and I've carefully documented the intricacies of doing so in Note [Loading classes from JIMAGE files] in Lang.JVM.Codebase. This is part of a fix for GaloisInc/saw-script#861.

[RyanGlScott]

I'm marking this as a draft for now since there appears to be a lurking bug that is uncovered when running crucible-jvm's test suite with JDK 11:

$ make clean && ./test.sh 
rm -f *.class
javac -g Str.java
Compiled from "Str.java"
class Str {
  Str();
    Code:
       0: aload_0
       1: invokespecial #1                  // Method java/lang/Object."<init>":()V
       4: return

  public static void main(java.lang.String[]);
    Code:
       0: ldc           #2                  // String 1234567890
       2: astore_1
       3: new           #3                  // class java/lang/StringBuffer
       6: dup
       7: aload_1
       8: invokespecial #4                  // Method java/lang/StringBuffer."<init>":(Ljava/lang/String;)V
      11: astore_2
      12: aload_2
      13: iconst_2
      14: ldc           #5                  // String abcd
      16: invokevirtual #6                  // Method java/lang/StringBuffer.insert:(ILjava/lang/String;)Ljava/lang/StringBuffer;
      19: pop
      20: getstatic     #7                  // Field java/lang/System.out:Ljava/io/PrintStream;
      23: aload_2
      24: invokevirtual #8                  // Method java/io/PrintStream.println:(Ljava/lang/Object;)V
      27: return
}
[Crux] Checking "Str.java"
starting executeCrucibleJVM
[Crux] Index 10 is not a method reference.
CallStack (from HasCallStack):
  error, called at src/Language/JVM/Parser.hs:387:12 in jvm-parser-0.3.0.0-inplace:Language.JVM.Parser

Amazingly, I haven't come across this before in the SAW test cases that I've ran, so I'm glad I thought to try this. I still need to figure out why this happens, however.

[RyanGlScott]

Per the discussion in GaloisInc/saw-script#861 (comment), I've unmarked this as a draft. The crucible-jvm tool now prints out a warning if you are using JDK 9 or later indicating that support for modern JDKs is still experimental, and the warning includes a pointer to #641. This warning should serve as a template for SAW.

[atomb]

This looks great. Thanks for including lots of design rationale documentation!