Clean up typescript types related to rust crypto (#4706)

* Simplify bootstrapSecretStorage logic

might as well just export the keys immediately, rather than having multiple
tests.

* Clean up typescript types related to rust crypto

A forthcoming release of matrix-rust-sdk-crypto-wasm tightens up a number of
typescript types. In preparation, we need to get our house in order too.

spec/unit/rust-crypto/KeyClaimManager.spec.ts

@@ -74,7 +74,8 @@ describe("KeyClaimManager", () => {
                     // ...  and we now resolve the original promise with the resolver for that second promise.
                     resolveCalledPromise(resolveCompletePromise);
                 });
-                return completePromise;
+                await completePromise;
+                return true;
             });
         });
     }
@@ -91,7 +92,7 @@ describe("KeyClaimManager", () => {
         fetchMock.postOnce("https://example.com/_matrix/client/v3/keys/claim", '{ "k": "v" }');
 
         // also stub out olmMachine.markRequestAsSent
-        olmMachine.markRequestAsSent.mockResolvedValueOnce(undefined);
+        olmMachine.markRequestAsSent.mockResolvedValueOnce(true);
 
         // fire off the request
         await keyClaimManager.ensureSessionsForUsers(new LogSpan(logger, "test"), [u1, u2]);