fix init command with environment variable

[abhishekkumams]

Why make this change?

• Closes [Bug]: DAB init doesn't honor DAB_ENVIRONMENT variable #1527
  • dab init doesn't create file with the environment Value, and always create default config if not specified explicitly.
  • For ex: if DAB_ENVIRONMENT is set to Development, it should create dab-config.Development.json, which is not the case.

What is this change?

• Updating the logic to create config file giving precedence to environment value, also making sure error is thrown if the file is not present already.

How was this tested?

• Unit Tests

Sample Request(s)

dab init --database-type mssql
above command will create:

1. DAB_ENVIRONMENT = null
   dab-config.json
2. DAB_ENVIRONMENT = Development
   dab-config.Development.json

[seantleonard]

Some questions and suggestions for simplification

[seantleonard]

Thanks for fixing! also for addressing comment, very clean. Appreciate the ability to see full file path in the logs, will help us/PMs/customers troubleshoot if necessary!

[Aniruddh25]

LGTM, after fixing some corner cases.

updated