Contracts move fixtures to new crate (#2246)

Small PR that introduce a new crate that will host RISC-V & wasm
fixtures for testing pallet-contracts

substrate/frame/contracts/fixtures/data/ok_trap_revert.wat

@@ -0,0 +1,35 @@
+(module
+	(import "seal0" "seal_input" (func $seal_input (param i32 i32)))
+	(import "seal0" "seal_return" (func $seal_return (param i32 i32 i32)))
+	(import "env" "memory" (memory 1 1))
+
+    (func (export "deploy")
+        (call $ok_trap_revert)
+    )
+
+    (func (export "call")
+        (call $ok_trap_revert)
+    )
+
+    (func $ok_trap_revert
+        (i32.store (i32.const 4) (i32.const 4))
+        (call $seal_input (i32.const 0) (i32.const 4))
+        (block $IF_2
+            (block $IF_1
+                (block $IF_0
+                    (br_table $IF_0 $IF_1 $IF_2
+                        (i32.load8_u (i32.const 0))
+                    )
+                    (unreachable)
+                )
+                ;; 0 = return with success
+                return
+            )
+            ;; 1 = revert
+            (call $seal_return (i32.const 1) (i32.const 0) (i32.const 0))
+            (unreachable)
+        )
+        ;; 2 = trap
+        (unreachable)
+    )
+)