added the capability to configure Loki without needing to rebuild the…

[Gordejj]

… operator

What this PR does / why we need it:
I added the capability to append template for Loki config without needing to rebuild the operator. In our case, we are developing a private cloud and want to provide logging as a service. This means that multiple user spaces will have clusters deployed with the loki-operator.
Therefore, we cannot rebuild the loki-operator for each such project individually. It's easier for us to create a template with the Loki configuration as an external dependency, which can be provided to the operator at runtime to modify the config-map and manually restart the components.
I understand the best way is to develop resources, but it seems that a quick workaround would also be useful.

Special notes for your reviewer:
Automatic restart for applying configuration changes is not provided, only a guarantee of modifying the YAML file is assured.
Updated the old test cases but did not add new ones.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• [] Documentation added
• Tests updated
• CHANGELOG.md updated
  • If the change is worth mentioning in the release notes, add add-to-release-notes label
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[CLAassistant]

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1 out of 2 committers have signed the CLA.

✅ Gordejj
❌ dmitry.gordeev

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