[TASK] Centralize configuration for TER API
A new Configuration class is added, which contains all information that was previously set in various places.
This change
- removes a dummy \stdObject containing random information
- removes dependencies revolving around implicit dependencies in TSFE setup variables
- Centralizes all options regarding repository path
In addition, the tx_ter_api object does need any external dependencies loaded from e.g. pi-based plugins anymore. This way, the next step is to build a middleware for /ter and removing the plugin alltogether.