Client refactor

[danvergara]

Client refactor

Description

The code involved with the queries build up is too attached to the client and hard-coded, adding a new database comes down to adding a new case to a switch, which is not optimal. The idea is refactor the client and abstract away the way queries are performed. This way, adding a new database will be basically a new struct implementing the databaseQuerier interface.

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?

Ran the test suite and QA'd every database supported.

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