Replicate javap's version flag

[ExcaliburZero]

Currently we do not take in any command line arguments and flags other than the class file to parse and report on. We also as of #5 have the capability to have the executable not include the code references in the program output.

It would be nice to try to have some flags similar to those provided by javap to configure the output of the executable. A good flag to start with would be the -verbose flag.

For example:

$ javap classes/Dummy.class 
Compiled from "Dummy.java"
public class Dummy {
  public Dummy();
}

$ javap -v classes/Dummy.class
Classfile /home/chris/Code/jvm-class-file-parser/classes/Dummy.class
  Last modified Jan 4, 2021; size 184 bytes
  MD5 checksum a1fc389a27d8a93ab140f4a1ecaa33b7
  Compiled from "Dummy.java"
public class Dummy
  minor version: 0
  major version: 55
  flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: #2                          // Dummy
  super_class: #3                         // java/lang/Object
  interfaces: 0, fields: 0, methods: 1, attributes: 1
Constant pool:
   #1 = Methodref          #3.#10         // java/lang/Object."<init>":()V
   #2 = Class              #11            // Dummy
   #3 = Class              #12            // java/lang/Object
   #4 = Utf8               <init>
   #5 = Utf8               ()V
   #6 = Utf8               Code
   #7 = Utf8               LineNumberTable
   #8 = Utf8               SourceFile
   #9 = Utf8               Dummy.java
  #10 = NameAndType        #4:#5          // "<init>":()V
  #11 = Utf8               Dummy
  #12 = Utf8               java/lang/Object
{
  public Dummy();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 1: 0
}
SourceFile: "Dummy.java"

[ExcaliburZero]

Relevant code section:

jvm-class-file-parser/src/main.rs

Line 23 in 5435b91

let javap_result = javap(filepath, false);