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/class_linker.cc b/runtime/class_linker.cc
index ecaa4c2..c51b99a 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -56,6 +56,8 @@
 #include "gc/space/image_space.h"
 #include "handle_scope-inl.h"
 #include "image-inl.h"
+#include "imt_conflict_table.h"
+#include "imtable-inl.h"
 #include "intern_table.h"
 #include "interpreter/interpreter.h"
 #include "jit/jit.h"
@@ -6268,7 +6270,7 @@
       // or interface methods in the IMT here they will not create extra conflicts since we compare
       // names and signatures in SetIMTRef.
       ArtMethod* interface_method = interface->GetVirtualMethod(j, image_pointer_size_);
-      const uint32_t imt_index = interface_method->GetImtIndex();
+      const uint32_t imt_index = ImTable::GetImtIndex(interface_method);
 
       // There is only any conflicts if all of the interface methods for an IMT slot don't have
       // the same implementation method, keep track of this to avoid creating a conflict table in
@@ -6322,7 +6324,7 @@
         }
         DCHECK(implementation_method != nullptr);
         ArtMethod* interface_method = interface->GetVirtualMethod(j, image_pointer_size_);
-        const uint32_t imt_index = interface_method->GetImtIndex();
+        const uint32_t imt_index = ImTable::GetImtIndex(interface_method);
         if (!imt[imt_index]->IsRuntimeMethod() ||
             imt[imt_index] == unimplemented_method ||
             imt[imt_index] == imt_conflict_method) {
@@ -6781,7 +6783,7 @@
         auto* interface_method = iftable->GetInterface(i)->GetVirtualMethod(j, image_pointer_size_);
         MethodNameAndSignatureComparator interface_name_comparator(
             interface_method->GetInterfaceMethodIfProxy(image_pointer_size_));
-        uint32_t imt_index = interface_method->GetImtIndex();
+        uint32_t imt_index = ImTable::GetImtIndex(interface_method);
         ArtMethod** imt_ptr = &out_imt[imt_index];
         // For each method listed in the interface's method list, find the
         // matching method in our class's method list.  We want to favor the