ART: Factor out IMT from ArtMethod

Move IMT Conflict Table to its own file. Move IMT index computation to
ImTable.

In preparation for code using this independent of specific ArtMethods.

Bug: 31594153
Test: m test-art-host
Change-Id: Ifd6e304bb86724c5284984c4655c43d3af357f84
diff --git a/runtime/image-inl.h b/runtime/image-inl.h
index 669649e..da18ae5 100644
--- a/runtime/image-inl.h
+++ b/runtime/image-inl.h
@@ -20,6 +20,7 @@
 #include "image.h"
 
 #include "art_method.h"
+#include "imt_conflict_table.h"
 #include "imtable.h"
 #include "read_barrier-inl.h"