fix(router): metadata field update in merchant_account and merchant_connector_account

[srujanchikke]

Type of Change

• [x] Bugfix
• [ ] New feature
• [x] Enhancement
• [ ] Refactoring
• [ ] Dependency updates

Description

metadata field in merchant_account is added in db . retrieval and updation of metadata in both merchant_account and merchant_connector_account are reflected in db

Additional Changes

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

Motivation and Context

metadata field was unable to retrieve and update because merchant_account doesn't have metadata field and updating function of merchant_connecter_account didn't add metadata.

How did you test it?

tested using postman

Checklist

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