PR Template for benchmark creation

[TLSDC]

Benchmark tutorial

This PR serves as a template for benchmark creation. It involves the following steps:

• Creating a task object to integrate your tasks to BrowserGym
• Registering said tasks to expose them through the gym.make interface. (see loop.py )
• Make your benchmark pip installable along with browsergym
• Define an action set for your benchmark
• Define a Benchmark object to use your benchmark in the AgentLab experiment setting
• Add basic Tests (see existing tests for inspiration)
• Update ReadMe