feat(events): Add events framework for registering events

[lsampras]

Type of Change

• [ ] Bugfix
• [ ] New feature
• [ ] Enhancement
• [ ] Refactoring
• [ ] Dependency updates
• [ ] Documentation
• [ ] CI/CD

Description

• Add a separate events crate for the events framework & implementation
• Add a request State that will handle the request scoped state
• This state can be mutable & is scoped to a particular request only
• Generate this state as part of server_wrap that can be used to collect the request metadata & mutable variables to be used

Additional Changes

• [ ] This PR modifies the API contract
• [ ] This PR modifies the database schema
• [ ] This PR modifies application configuration/environment variables

Motivation and Context

• Adding events framework would need a request scoped context
• In order to satisfy all such requirements of passing around a mutable state/variables we've added the RequestState that would be valid for the duration for a request
• Since this State represents the request variables pertaining to the request such as flow / request id / trace id / connector etc can be easily recorded along with other domain variables

How did you test it?

• Since this PR doesn't involve any new functionality I just ran the postman tests with stripe to verify this

Checklist

• [x] I formatted the code cargo +nightly fmt --all
• [x] I addressed lints thrown by cargo clippy
• [x] I reviewed the submitted code
• [ ] I added unit tests for my changes where possible
• [ ] I added a CHANGELOG entry if applicable