cranelift: move wasmtests in cranelift-wasm

Move test data used by cranelift-wasm's tests in
the crate directory, to make the tests autonomous.

Fixes #2910

cranelift/wasm/wasmtests/passive-data.wat

@@ -0,0 +1,12 @@
+(module
+  (data $passive "this is a passive data segment")
+  (memory 0)
+
+  (func (export "init") (param i32 i32 i32)
+    local.get 0 ;; dst
+    local.get 1 ;; src
+    local.get 2 ;; cnt
+    memory.init $passive)
+
+  (func (export "drop")
+    data.drop $passive))