feat: support metadrive env

[Gaiejj]

Description

This PR is already complete in terms of implementation accuracy. We will merge it shortly after improving the code style and documentation.

This PR supports SafeMetaDrive from MetaDrive[1].

[1]: Metadrive: Composing diverse driving scenarios for generalizable reinforcement learning

Autonomous driving is an important application of reinforcement learning algorithms, and safety is particularly crucial. Safety constraints for autonomous driving tasks are an important research direction in the SafeRL field. We have implemented the embedding of SafeMetaDrive based on our customized environment interface (more details in #310 ) and presented the SafeRL baseline algorithms involved in the MetaDrive paper as follows, hoping to inspire research on related algorithms.

Motivation and Context

Related issues can be found at #262

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[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 96.83%. Comparing base (924f74c) to head (bd62803).

Files	Patch %	Lines
omnisafe/evaluator.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #328      +/-   ##
==========================================
- Coverage   96.84%   96.83%   -0.01%     
==========================================
  Files         138      138              
  Lines        7060     7071      +11     
==========================================
+ Hits         6837     6847      +10     
- Misses        223      224       +1     

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[muchvo]

LGTM.