saip-tool: Add 'extract-apps' to dump all applications from eSIM profile

This new action can be used to dump all java applications as either raw
IJC file or converted to CAP format (the usual format generated by
JavaCard toolchains).

Change-Id: I51cffa5ba3ddbea491341d678ec9249d7cf470a5

pySim/javacard.py

@@ -0,0 +1,19 @@
+# JavaCard related utilities
+
+import zipfile
+import struct
+import sys
+import io
+
+def ijc_to_cap(in_file: io.IOBase, out_zip: zipfile.ZipFile, p : str = "foo"):
+    """Convert an ICJ (Interoperable Java Card) file [back] to a CAP file."""
+    TAGS = ["Header", "Directory", "Applet", "Import", "ConstantPool", "Class", "Method", "StaticField", "RefLocation", "Export", "Descriptor", "Debug"]
+    b = in_file.read()
+    while len(b):
+        tag, size = struct.unpack('!BH', b[0:3])
+        out_zip.writestr(p+"/javacard/"+TAGS[tag-1]+".cap", b[0:3+size])
+        b = b[3+size:]
+
+# example usage:
+# with io.open(sys.argv[1],"rb") as f, zipfile.ZipFile(sys.argv[2], "wb") as z:
+#     ijc_to_cap(f, z)