[icat] add support for sample name and description. The level above the dataset is no longer called "sample" but "collection".

transform scan_saving.proposal .sample .dataset into respective objects and add .proposal_name, .sample_name, .dataset_name to scan_saving to replace the old .proposal .sample .dataset

- split installation in two sections: one for ESRF, one outside ESRF
- move ESRF data policy servers setup to ESRF installation chapter