Rename BootImageModule to BootclasspathFragmentModule

Also renames files, tests, module types in a similar fashion.

There are still some references to image and boot image. They are kept
for the following reasons:
* image_name - this is the name of an ART boot image, i.e. the
  collection of .art/.oat/.vdex files.
* BootImageInfo - again this is related to the ART boot image.
* .../art_boot_images/... paths - ditto.

Bug: 177892522
Test: m nothing
Change-Id: Ie1f4738061d131fee75de48bc26a7601481bad4d
diff --git a/apex/Android.bp b/apex/Android.bp
index 7b52402..e234181 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -30,7 +30,7 @@
     ],
     testSrcs: [
         "apex_test.go",
-        "boot_image_test.go",
+        "bootclasspath_fragment_test.go",
         "platform_bootclasspath_test.go",
         "vndk_test.go",
     ],