Add rollout_buffer_class to TRPO

[ernestum]

Description

This adds the rollout_buffer_class to TRPO in sync with DLR-RM/stable-baselines3#1720. I decided not to add it to MaskeablePPO and RecurrentPPO since they require special rollout buffers.

Context

• I have raised an issue to propose this change (required)

Types of changes

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

Checklist:

• I've read the CONTRIBUTION guide (required)
• The functionality/performance matches that of the source (required for new training algorithms or training-related features).
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have included an example of using the feature (required for new features).
• I have included baseline results (required for new training algorithms or training-related features).
• I have updated the documentation accordingly.
• I have updated the changelog accordingly (required).
• I have reformatted the code using make format (required)
• I have checked the codestyle using make check-codestyle and make lint (required)
• I have ensured make pytest and make type both pass. (required)

Note: we are using a maximum length of 127 characters per line

[araffin]

Fyi, I already did a pre-release https://pypi.org/project/stable-baselines3/2.2.0a9/, and you would need it to build this SB3 contrib version ;)

[ernestum]

Oh nice thanks!