refactor(cmd-api-server): migrate from convict to yargs

[petermetz]

Description

Pros and cons wise yargs wins out based on my recent experience with using both.

Convict cannot express certain things correctly in the configuration schema which makes it slightly harder to understand, specifically when it comes to asking in JSON strings as configuration parameters.

Acceptance Criteria

1. Convict is no longer a dependency in the project
2. Configuration parsing works as before, e.g. the existing config.json files, the CLI -> ENV -> FILE predence is kept
3. API server is able to print it's own command line help message going through all the commands providing examples as before.

[Leeyoungone]

Hello! May I take up this issue?

[petermetz]

@Leeyoungone Of course, all yours! Thank you!

[RafaelAPB]

Until there is an explicit need for this feature, this issue is closed.