feat(payments): add api locking for payments core

[Abhicodes-crypto]

Type of Change

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

Description

This PR introduces an API locking framework and uses it with the core payments flow. For now both are under the locking feature flag. After thorough testing they can be moved under release feature.
Problem statement:

• When webhooks, sync, redirection happen almost at the same time there could be race conditions and inconsistency in the status of the payment.
• What if capture and cancel happens at the same time.

API locking prevents that by locking the flow.

• Another use case of API locking, while attempting to not send duplicate webhooks to merchant, the logic was to fetch a table from DB and then check a value if it is false send the webhook or else don't send it . But if some other request changes the value to true after the previous request fetches it. Here race condition could happen and multiple webhooks could still be done. So API locking can solve this.

TODO :

• Add status validations.
• Speculate what action should be taken in case of validation fails.
• Add logs.
• Add metrics
• Remove hard coded values and take config from Redis.
• What action to take when the retries are exhausted.
• Refactor such that the get_key_and_lock_resource function returns only the status Acquired or gives error and only over acquired status release_lock is implemented.
• Code clean up

Additional Changes

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

Motivation and Context

How did you test it?

Monitored redis if the locks are getting created or not.

Webhooks testing still in progress

Checklist

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