FTRS-2587 Data migration toggles

[lukasz-jercha-nhs]

Description

• removed example toggle usage from queue populator lambda
• implemented toggle usage criteria from FTRS-2587
• updated main.py cli script to support direct execution (PyCharm debugging)
• updated feature toggle client to support offline mode (use .env values for feature toggle instead of AWS AppConfig
• updated processor tests to use mocked supported transformer (field mappings already tested by other tests)

Context

---

Sensitive Information Declaration

To ensure the utmost confidentiality and protect your and others privacy, we kindly ask you to NOT including PII (Personal Identifiable Information) / PID (Personal Identifiable Data) or any other sensitive data in this PR (Pull Request) and the codebase changes. We will remove any PR that do contain any sensitive information. We really appreciate your cooperation in this matter.

• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.

[nhs-shruthi-gowda]

Nice