As a **developer**,
**I want** to prevent accidental errors,
**so that** I can safely A/B test new features
Acceptance Criteria:
* There is a command added to the FundraisingFrontend console that validates the `camapigns.yml` file according to the following criteria:
* The indentation is correct
* All required parameters are present
* The start and end dates must be quoted and in the format `YYYY-MM-DD` or `YYYY-MM-DD H:i:s`. All dates are considered to be in the Europe/Berlin timezone.
* The end date must be after the start date.
* The `default_bucket` must be part of the `buckets` definition.
* Bucket names beginning with digits (e.g. `10h16`) must be quoted, both for `buckets` and `default_bucket`.
* Ensure that all buckets are unique
* The validation command is added to the CI ( `ci` task in the Makefile)
Background:
Basic checks for required parameters and correct structure of the file are already done by the `CategoryConfiguration` class.
This task is different from {T196929}, which is about checking if the code actually implements the campaigns described in the configuration file.