feat: support interface of environment customization

[Gaiejj]

Description

• Supports interfaces for customized environments;
• Provides corresponding API documentation;
• Releases tutorials for customized environments in both Chinese and English.

Motivation and Context

The environment customization interface is an important feature (see #291, #285, #305) OmniSafe Team. As a toolkit to accelerate SafeRL research, we offer a flexible environment customization interface with the following characteristics:

• Almost unrestricted creation of customized environments
• Parameter passing for environment creation
• Recording of environment training information

Most importantly, users can embed their environments into the OmniSafe training framework with little to no modification of OmniSafe's source code. We provide detailed API documentation and tutorials for the SafeRL community to reference.

• [x] 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? Put an x in all the boxes that apply:

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

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!

• [x] I have read the CONTRIBUTION guide. (required)
• [x] My change requires a change to the documentation.
• [x] I have updated the tests accordingly. (required for a bug fix or a new feature)
• [x] I have updated the documentation accordingly.
• [x] I have reformatted the code using make format. (required)
• [x] I have checked the code using make lint. (required)
• [x] I have ensured make test pass. (required)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 72.47706% with 30 lines in your changes are missing coverage. Please review.

Project coverage is 96.56%. Comparing base (51a2692) to head (673ce70).

Files	Patch %	Lines
omnisafe/envs/custom_env.py	59.18%	20 Missing :warning:
omnisafe/adapter/offpolicy_adapter.py	66.67%	1 Missing :warning:
omnisafe/adapter/online_adapter.py	93.33%	1 Missing :warning:
omnisafe/adapter/onpolicy_adapter.py	50.00%	1 Missing :warning:
omnisafe/algorithms/off_policy/ddpg.py	66.67%	1 Missing :warning:
...isafe/algorithms/on_policy/base/policy_gradient.py	75.00%	1 Missing :warning:
omnisafe/envs/core.py	90.91%	1 Missing :warning:
omnisafe/envs/mujoco_env.py	66.67%	1 Missing :warning:
omnisafe/envs/safety_gymnasium_modelbased.py	66.67%	1 Missing :warning:
omnisafe/evaluator.py	83.33%	1 Missing :warning:
... and 1 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #310 +/- ## ========================================== - Coverage 96.89% 96.56% -0.33% ========================================== Files 138 139 +1 Lines 7000 7089 +89 ========================================== + Hits 6782 6845 +63 - Misses 218 244 +26 ```

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