feature: update function to handle localhost properly

[Anmol1696]

This pull request updates the send-email-link function to improve local development flexibility and configuration. The primary change is to introduce a new ALLOW_LOCALHOST environment variable, which enables the use of http and custom ports for localhost URLs, replacing the previous logic that relied on dry-run mode. This allows for safer and more intentional local testing. Additionally, the handling of the LOCAL_APP_PORT environment variable is streamlined.

Configuration and Local Development Improvements:

• Added support for the ALLOW_LOCALHOST environment variable to explicitly enable http protocol and custom ports for localhost URLs, decoupling this behavior from dry-run mode. (functions/send-email-link/src/index.ts)
• Updated the construction of local URLs to use ALLOW_LOCALHOST and LOCAL_APP_PORT instead of relying on dry-run mode, improving clarity and control for local development. (functions/send-email-link/src/index.ts)
• Included allowLocalhost in the logger output and standardized the use of the localAppPort variable for reporting, ensuring consistency in diagnostics and debugging. (functions/send-email-link/src/index.ts)