[Algorithm] Update DQN example

[albertbou92]

Description

Reproduce known DQN benchmarks.

Motivation and Context

Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.
You can use the syntax close #15213 if this solves the issue #15213

• I have raised an issue to propose this change (required for new features and bug fixes)

Types of changes

What types of changes does your code introduce? Remove all that do not apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds core functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)
• Example (update in the folder of examples)

Checklist

Go over all the following points, and put an x in all the boxes that apply.
If you are unsure about any of these, don't hesitate to ask. We are here to help!

• I have read the CONTRIBUTION guide (required)
• My change requires a change to the documentation.
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have updated the documentation accordingly.

[vmoens]

LGTM, some minor comments

[vmoens]

Benchmarks in the repo is intended for runtime benchmark.
I would call this evaluation. At the end of the day, I think that what we will want is the following directory tree:

torchrl/
    ├── benchmarks/
    │   ├── component_x/
    │   │   ├── benchmark_workflow_1/
    │   │   ├── benchmark_workflow_2/
    │   │   └── ...
    │   ├── algorithm_y/
    │   │   ├── benchmark_workflow_1/
    │   │   ├── benchmark_workflow_2/
    │   │   └── ...
    │   └── ...
    ├── evaluation/
    │   ├── component_x/
    │   │   ├── evaluation_metrics_1/
    │   │   ├── evaluation_metrics_2/
    │   │   └── ...
    │   ├── algorithm_y/
    │   │   ├── evaluation_metrics_1/
    │   │   ├── evaluation_metrics_2/
    │   │   └── ...
    │   └── ...
    └── ...

cc @matteobettini @BY571

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/rl/1512

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

✅ You can merge normally! (9 Unrelated Failures)

As of commit 97e7aa5 with merge base 25bd8a5 ():

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• Build M1 Wheels / pytorch/rl / wheel-py3_8-cpu (gh)
• Continuous Benchmark (PR) / CPU Pytest benchmark (gh)
• Continuous Benchmark (PR) / GPU Pytest benchmark (gh)
• Olddeps Tests on Linux / unittests (3.8, 11.6) / linux-job (gh)
• Unit-tests on MacOS CPU / tests (3.8) / macos-job (gh)
• Unit-tests on Windows CPU / unittests / windows-job (gh)
• Unit-tests on Windows GPU / unittests / windows-job (gh)

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• Habitat Tests on Linux / tests (3.9, 11.6) / linux-job (gh)
• RLHF Tests on Linux / unittests (3.9, 12.1) / linux-job (gh)

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[vmoens]

@albertbou92 the example CI is failing bc we did not update the runs there