[twisty] Remove warning for setting TwistyPlayer alg using string.

This will depend on microsoft/TypeScript#42425 landing in stable TypeScript so we can update the types to reflect it.

src/cubing/twisty/dom/TwistyPlayer.spec.ts

@@ -1,5 +1,6 @@
 import { Alg } from "../../alg";
 import { TwistyPlayer } from "./TwistyPlayer";
+import "../../alg/test/alg-comparison";
 
 describe("TwistyPlayer", () => {
   it("can be constructed", () => {
@@ -8,4 +9,14 @@ describe("TwistyPlayer", () => {
     });
     expect(twistyPlayer.alg.experimentalNumUnits()).toEqual(3);
   });
+
+  it("can set alg using string", () => {
+    const twistyPlayer = new TwistyPlayer({
+      alg: new Alg("R U R'"),
+    });
+    // TODO(https://github.com/microsoft/TypeScript/pull/42425): remove `@ts-ignore`.
+    // @ts-ignore
+    twistyPlayer.alg = "F2";
+    expect(twistyPlayer.alg).toBeIdentical(new Alg("F2"));
+  });
 });

src/cubing/twisty/dom/TwistyPlayer.ts

@@ -127,13 +127,11 @@ export class TwistyPlayer extends ManagedCustomElement {
     this.#legacyExperimentalPG3DViewConfig = legacyExperimentalPG3DViewConfig;
   }
 
-  set alg(newAlg: Alg) {
+  // TODO(https://github.com/microsoft/TypeScript/pull/42425): Allow setting string in the type decl.
+  set alg(newAlg: Alg /* | string*/) {
     // TODO: do validation for other algs as well.
     if (typeof newAlg === "string") {
-      console.warn(
-        "`alg` for a `TwistyPlayer` was set using a string. It should be set using a `Sequence`!",
-      );
-      newAlg = new Alg((newAlg as unknown) as string);
+      newAlg = Alg.fromString(newAlg);
     }
     this.#config.attributes["alg"].setValue(newAlg);
     this.cursor?.setAlg(newAlg, this.indexerConstructor()); // TODO: can we ensure the cursor already exists?