Use yaml unmarshaller instead of json's

[jotak]

Description

• This works without changing the input as YAML is a superset of JSON
• This allows to get rid of our prometheus model override, which was due to a bug when using JSON unmarshaller
• Refactor / simplify tests and confgen, doing less of the decode/reencode magic

Dependencies

n/a

Checklist

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  • [ ] Regression tests only (e.g. refactoring with no user-facing change).
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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 67.30%. Comparing base (24bf8ce) to head (873e42c).

Files	Patch %	Lines
pkg/confgen/extract.go	50.00%	1 Missing :warning:
pkg/config/config.go	66.66%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #622 +/- ## ========================================== + Coverage 67.22% 67.30% +0.07% ========================================== Files 104 104 Lines 7459 7416 -43 ========================================== - Hits 5014 4991 -23 + Misses 2143 2126 -17 + Partials 302 299 -3 ``` | [Flag](https://app.codecov.io/gh/netobserv/flowlogs-pipeline/pull/622/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netobserv) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/netobserv/flowlogs-pipeline/pull/622/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netobserv) | `67.30% <85.71%> (+0.07%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=netobserv#carryforward-flags-in-the-pull-request-comment) to find out more.

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[jotak]

Attempt fails, cf https://github.com/netobserv/flowlogs-pipeline/pull/623 We'd need to get rid of viper if we want to use yaml rather than json. I don't think viper brings anything super useful here, anyway.

[KalmanMeth]

@eranra I think viper was originally used to allow passing in command line configuration parameters. We need to decide whether we still need this.

[jotak]

@KalmanMeth yes it allows using various sources for parameters, but comes with this limitation of not being case sensitive which is annoying for yaml. Do you have any idea if the other parameter sources (such as ENV or command line) are actually used out in the wild?

[eranra]

@KalmanMeth yes it allows using various sources for parameters, but comes with this limitation of not being case sensitive which is annoying for yaml. Do you have any idea if the other parameter sources (such as ENV or command line) are actually used out in the wild?

@jotak @KalmanMeth In past projects we used cobra https://github.com/spf13/cobra - I do not know if this is better in compared with viper. In any event, I think that for the completeness and simplicity of a "stand-alone" tool such as FLP it does make sense to keep the option to provide command-line parameters