[ENH] - Add functionality to directly support 1D counts collection & collections across time

[TomDonoghue]

Main updates:

• Addition of Counts1D object, allowing for collecting the counts across a single set of terms (no co-occurrences)
• Add a copy method to objects, and update metadata tracking to track search settings
• Add a collect_across_time collection function to run searches across date ranges, with associated IO & plot functions
• Update collection procedures, allowing to skip db info collection and update Requester use & metadata collection
• Update MetaData object including adding save & load functionality
• Some internal reorganizations of the module (new io sub-module, moving utils, etc)
• Update IO approach to fully & consistently use Paths objects
• Add plotting helper function for rotating tick labels