Replace internal usages of @iov/encoding with @cosmjs/{encoding,math}

packages/utils/types/index.d.ts

@@ -1,2 +1,3 @@
 export { assert } from "./assert";
 export { sleep } from "./sleep";
+export { isNonNullObject, isUint8Array } from "./typechecks";

packages/utils/types/typechecks.d.ts

@@ -0,0 +1,8 @@
+/**
+ * Checks if data is a non-null object (i.e. matches the TypeScript object type)
+ */
+export declare function isNonNullObject(data: unknown): data is object;
+/**
+ * Checks if data is an Uint8Array. Note: Buffer is treated as not a Uint8Array
+ */
+export declare function isUint8Array(data: unknown): data is Uint8Array;