Fix/remove city enum usage

[jaypalmudaliyar24]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates

Description

• Removes City enum usage across repository.
• Added Update Cities API which can append or replace list of cities.
• Related nammayatri PR

Additional Changes

• This PR modifies the database schema (database migration added)
• This PR modifies dhall configs/environment variables

• Added internalAuthApiKey to add authentication in Update City API.

Motivation and Context

• Because we require dependency update every time new City enum is added, it requires a new deployment otherwise immediate switch to this registry and gateway causes parsing issue. So made the city field across repo as Text which is expected to be the std code of city.
• created api to update list of cities, so no db queries are required to update it.

How did you test it?

• Tested locally and added relevant test in nammayatri repo.

Checklist

• I formatted the code and addressed linter errors ./dev/format-all-files.sh
• I reviewed submitted code
• I added unit tests for my changes where possible
• I added a CHANGELOG entry if applicable