docs: update sidebar + embed youtube video (#2470)

Moves the testing with typescript tutorials to tutorials and embed
recording from Privacy + Scaling Explorations into the indexed merkle
tree section.

docs/docs/concepts/advanced/data_structures/indexed_merkle_tree.md

@@ -9,6 +9,10 @@ import Disclaimer from "../../../misc/common/\_disclaimer.mdx";
 
 ## Indexed Merkle Trees
 
+This article will introduce the concept of an indexed merkle tree, and how it can be used to improve the performance of nullifier trees in circuits. The content was also covered in a presentation for the [Privacy + Scaling Explorations team at the Ethereum Foundation](https://pse.dev/).
+
+<iframe width="100%" height="720" src="https://www.youtube-nocookie.com/embed/x_0ZhUKtWSs?si=TmguEhgz4Gu07Dac" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>
+
 #### Primer on Nullifier Trees
 
 Currently the only feasible way to get privacy in public blockchains is via a UTXO model. In this model, state is stored in encrypted UTXO's in merkle trees. However, to maintain privacy, state can not be updated. The very act of performing an update leaks information. In order to simulate "updating" the state, we "destroy" old UTXO's and create new ones for each state update. Resulting in a merkle tree that is append-only.

docs/docs/dev_docs/testing/testing.md → docs/docs/dev_docs/tutorials/testing.md

@@ -127,7 +127,7 @@ In the near future, transactions where a public function call fails will get min
 
 We can check private or public state directly rather than going through view-only methods, as we did in the initial example by calling `token.methods.balance().view()`. Bear in mind that directly accessing contract storage will break any kind of encapsulation.
 
-To query storage directly, you'll need to know the slot you want to access. This can be checked in the [contract's `Storage` definition](../contracts/syntax/storage.md) directly for most data types. However, when it comes to mapping types, as in most EVM languages, we'll need to calculate the slot for a given key. To do this, we'll use the `CheatCodes` utility class:
+To query storage directly, you'll need to know the slot you want to access. This can be checked in the [contract's `Storage` definition](../contracts/syntax/storage.md) directly for most data types. However, when it comes to mapping types, as in most EVM languages, we'll need to calculate the slot for a given key. To do this, we'll use the [`CheatCodes`](./../testing/cheat_codes.md) utility class:
 
 #include_code calc-slot /yarn-project/end-to-end/src/guides/dapp_testing.test.ts typescript
 
@@ -163,7 +163,7 @@ We can query the RPC server for the unencrypted logs emitted in the block where
 
 ## Cheats
 
-The `CheatCodes` class, which we used for [calculating the storage slot above](#state), also includes a set of cheat methods for modifying the chain state that can be handy for testing.
+The [`CheatCodes`](./../testing/cheat_codes.md) class, which we used for [calculating the storage slot above](#state), also includes a set of cheat methods for modifying the chain state that can be handy for testing.
 
 ### Set next block timestamp
 

docs/docs/dev_docs/tutorials/writing_dapp/testing.md

@@ -4,7 +4,7 @@ title: Testing
 
 To wrap up this tutorial, we'll set up a simple automated test for our dapp contracts. We will be using [jest](https://jestjs.io/), but any nodejs test runner works fine.
 
-Here we'll only test the happy path for a `transfer` on our private token contract, but in a real application you should be testing both happy and unhappy paths, as well as both your contracts and application logic. Refer to the full [testing guide](../../testing/testing.md) for more info on testing and assertions.
+Here we'll only test the happy path for a `transfer` on our private token contract, but in a real application you should be testing both happy and unhappy paths, as well as both your contracts and application logic. Refer to the full [testing guide](../testing.md) for more info on testing and assertions.
 
 ## Dependencies
 
@@ -32,7 +32,7 @@ import TokenContractAbi from "../contracts/token/target/Token.json" assert { typ
 describe("token", () => {});
 ```
 
-Let's set up our test suite. We'll start [a new Sandbox instance within the test](../../testing/testing.md#running-sandbox-in-the-nodejs-process), create two fresh accounts to test with, and deploy an instance of our contract. The `aztec-sandbox` and `aztec.js` provide the helper functions we need to do this:
+Let's set up our test suite. We'll start [a new Sandbox instance within the test](../testing.md#running-sandbox-in-the-nodejs-process), create two fresh accounts to test with, and deploy an instance of our contract. The `aztec-sandbox` and `aztec.js` provide the helper functions we need to do this:
 
 #include_code setup yarn-project/end-to-end/src/sample-dapp/index.test.mjs javascript
 
@@ -44,7 +44,7 @@ Now that we have a working test environment, we can write our first test for exe
 
 #include_code test yarn-project/end-to-end/src/sample-dapp/index.test.mjs javascript
 
-In this example, we assert that the `recipient`'s balance is increased by the amount transferred. We could also test that the `owner`'s funds are decremented by the same amount, or that a transaction that attempts to send more funds than those available would fail. Check out the [testing guide](../../testing/testing.md) for more ideas.
+In this example, we assert that the `recipient`'s balance is increased by the amount transferred. We could also test that the `owner`'s funds are decremented by the same amount, or that a transaction that attempts to send more funds than those available would fail. Check out the [testing guide](../testing.md) for more ideas.
 
 ## Running our tests
 

docs/sidebars.js

@@ -224,6 +224,7 @@ const sidebars = {
             "dev_docs/tutorials/writing_dapp/testing",
           ],
         },
+        "dev_docs/tutorials/testing",
       ],
     },
 
@@ -319,7 +320,7 @@ const sidebars = {
         type: "doc",
         id: "dev_docs/testing/main",
       },
-      items: ["dev_docs/testing/testing", "dev_docs/testing/cheat_codes"],
+      items: ["dev_docs/testing/cheat_codes"],
     },
 
     {