- Reduce log messages

- `common` > `tests` > `InMemoryObjectDatabase.py`: enhance log error reporting
- `common` > `tools` > `descriptor` > `Tools.py`: correct formatting of non-string resource_values in custom config rules in method `format_custom_config_rules()`
- `common` > `tools` > `service` > `GenericRestServer.py`: correct format of reported listen URL

- InMemoryObjectDatabase: Corrected default log level and initialization of internal database
- InMemoryTimeSeriesDatabase: Corrected default log level
- MockServicerImpl_Context: Migrated to use InMemoryObjectDatabase and corrected default log level
- MockServicerImpl_Monitoring: Corrected default log level and log messages; fixed method signatures and imports

- Implemented InMemoryObjectDatabase
- Implemented InMemoryTimeSeriesDatabase
- Extended Mock Monitoring with KPIDescriptor management and retrieval of timeseries data from pandas DataFrame