[MAIN] [STRATCONN-6302] : Make the fields secret in cloud mode and browser mode destinations

[Prithviraj-rathore-segment]

JIRA

https://twilio-engineering.atlassian.net/browse/STRATCONN-6302

A summary of your pull request, including the what change you're making and why.

Description

1. This PR includes changes for making the fields secret in cloud mode and browser mode destinations.
2. Changes include the type: password for the secret fields

Testing

Testing done in staging environment . please find the attached testing document .
https://docs.google.com/document/d/1TOiGnM0iUwstZIby_wZE-EqsJAMppRPWIecrbdXqRXI/edit?tab=t.0

Include any additional information about the testing you have completed to
ensure your changes behave as expected. For a speedy review, please check
any of the tasks you completed below during your testing.

• Added unit tests for new functionality
• Tested end-to-end using the local server
• [If destination is already live] Tested for backward compatibility of destination. Note: New required fields are a breaking change.
• [Segmenters] Tested in the staging environment
• [Segmenters] [If applicable for this change] Tested for regression with Hadron.

Security Review

Please ensure sensitive data is properly protected in your integration.

• Reviewed all field definitions for sensitive data (API keys, tokens, passwords, client secrets) and confirmed they use type: 'password'