Multi config support

[danvergara]

Pull Request Template

Description

A user requested a very interesting feature on #137. Said feature is about to having multiple database configs, in order to have different database connection available defined in the .dblab.yaml file.

Example:

database:
  - name: "test"
    host: "localhost"
    port: 5432
    db: "users"
    password: "password"
    user: "postgres"
    schema: "public"
    driver: "postgres"
  - name: "prod"
    # example endpoint
    host: "mydb.123456789012.us-east-1.rds.amazonaws.com"
    port: 5432
    db: "users"
    password: "password"
    user: "postgres"
    schema: "public"
    driver: "postgres"
limit: 50

I agreed on the usefulness of this feature since I wanted to implemented before.
Such a change could result in a non backward compatible feature, since some users would leave the .dblab.yaml file untouched after the next update. We can permit us such proceeding since we're still under 0.X.X version though, the API is not stable yet.

The new way to consume this is:

$ dblab --config --cfg-name "prod"

--cfg-name can be omitted the default values is gonna be first item on the database array:

$ dblab --config

Fixes #137

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Tested it under quite a few different config files versions and scenarios.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have checked my code and corrected any misspellings

[valerybriz]

Looks very good I think it is an excellent feature since in most of the cases we have multiple versions of the "same" DB for pre-production, production, dev, etc..

[valerybriz]

💯

[israteneda]

LGTM! too, nice feature 🚀