Support .offset and .length for calldata bytes and string arrays.

test/libsolidity/semanticTests/inlineAssembly/calldata_offset_read_write.sol

@@ -0,0 +1,18 @@
+contract C {
+    function f(uint, bytes calldata x, uint) public returns (uint r, uint v) {
+        assembly {
+            x.offset := 8
+            x.length := 20
+        }
+        assembly {
+            r := x.offset
+            v := x.length
+        }
+    }
+}
+
+// ====
+// compileViaYul: also
+// ----
+// f(uint256,bytes,uint256): 7, 0x60, 8, 2, 0 -> 8, 0x14
+// f(uint256,bytes,uint256): 0, 0, 0 -> 8, 0x14