Clean up the Global _active_session and provide a better alternative (Parent)

[noklam]

Notes:

1. The scope of this PR will be limited to an ad-hoc fix so it doesn't block new session in Jupyter/Databricks environment when an active session is not closed.
2. The discussion of removing global _active_session will be deferred. Particularly, we will need more information about how the plugins developers are using it and do we need to expose more. Potentially adding new hooks/changing hookspec or some more thinking about the responsibility of KedroSession & KedroContext.

Originally posted by @noklam in #1434 (comment)

Follow up issues/PRs:

• Adding a new after_context_created hook into Kedro's hooks collection #1458
• Revisit: Make KedroContext a dataclass and add config_loader as a property #1459
• Removing KedroContext params and catalog hot-reload #1460

[antonymilne]

See #506 for some discussion of adding new arguments to the hook spec or creating a whole new hook. My initial proposal: #506 (comment)

[noklam]

Conclusion from today's discussion:

• Turn KedroContext into a dataclass
• Add the config_loader property so people don’t need to use context._getconfig_loader
• Add after_context_created hook and include KedroContext in the signature.
  For 0.19 - deprecating catalog and param hot reload.

[astrojuanlu]

I think most of the tasks here were done? And if there's only one task left, can we close this parent issue and leave the other one open?