Store input file list in subdir, add user hook to edit analysis cfg

• When launching many jobs the output directory becomes crowded with the txt files containing the input file lists -> store them in a subdirectory (cannot store them in batch/input because the batch backend is created later).
• In some cases a module should only run on a subset of all available samples (e.g. to inspect the properties of signal samples at gen-level). Currently that would require maintaining separate analysis.yml config files and hence duplicate a lof of information... this adds an user hook to edit the config dict before it is used to create any jobs.