refactor!: cli config with viper consolidation - step 1

[gjermundgaraba]

Description

Closes: #XXXX

The first step of multiple to deal with #9034. As per the discussion there I have tried to limit the PR down, but I was not able to do so without any breaking changes and actually making some meaningful examples of how to use the new setup.

The goal with this PR is to agree on the general approach and get the framework in place to clean up the way we do CLI configuration ("client" and "server").

The next steps would be to rewrite how flags and environmental variables are handled, which would touch a lot of tests that need to set up the ClientContex with Viper in order to function.

The general idea of how this would work can be seen in an initial draft I made here: gjermundgaraba@c2c443e?diff=split#diff-146f73b0327c426deb3126e44f9234c7a6fe190c1bcb4c98ab8366b3485922ed

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[tac0turtle]

sorry for not getting to this. @alexanderbez wanna give feedback?