New integrator, and add some metadata to integrators.py

[reubenharry]

Addresses #679

• [x] We should be able to understand what the PR does from its title only;
• [x] There is a high-level description of the changes;
• [x] There are links to all the relevant issues, discussions and PRs;
• [x] The branch is rebased on the latest main commit;
• [x] Commit messages follow these guidelines;
• [x] The code respects the current naming conventions;
• [x] Docstrings follow the numpy style guide
• [x] pre-commit is installed and configured on your machine, and you ran it before opening the PR;
• [x] There are tests covering the changes;
• [x] The doc is up-to-date;

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 46.00000% with 27 lines in your changes are missing coverage. Please review.

Project coverage is 97.79%. Comparing base (7cf4f9d) to head (06dd04d). Report is 8 commits behind head on main.

:exclamation: Current head 06dd04d differs from pull request most recent head abe707c

Please upload reports for the commit abe707c to get more accurate results.

Files	Patch %	Lines
blackjax/mcmc/integrators.py	46.00%	27 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #681 +/- ## ========================================== - Coverage 98.87% 97.79% -1.09% ========================================== Files 59 59 Lines 2745 2806 +61 ========================================== + Hits 2714 2744 +30 - Misses 31 62 +31 ```

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[reubenharry]

I see that code coverage is complaining about integrator_order, name_integrator and calls_per_integrator_step. These seem useful, but depending on your view, I could remove them

[junpenglao]

I see that code coverage is complaining about integrator_order, name_integrator and calls_per_integrator_step. These seem useful, but depending on your view, I could remove them

Yeah please remove them, depending on what you want to check there should be better ways to return these properties.