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/float_instruction.wat

@@ -0,0 +1,12 @@
+;; Module that contains a float instruction which is illegal in deterministic mode
+(module
+	(import "env" "memory" (memory 1 1))
+	(func (export "call")
+		f32.const 1
+		drop
+	)
+	(func (export "deploy")
+		f32.const 2
+        drop
+	)
+)