Tracking Issue: Breaking filename dependency

[charles-turner-1]

This tracking issue is to collate everything relating to using filenames to build datastores.

• Rewrite builders to extract relevant info from netCDF files, rather than regex matching on filenames #378
• 489 - OM3 Builder can now extract realm from file attributes #478
• Clarify extent to which filename regex'ing is still necessary #474
• Extend OM3 regex to include additional patterns #459
• New CICE5 names will break the esm1.5/6 builder #466
• AccessESM1.6 Builder #412
• [DATA REQUEST] Add AUS2200 datasets #319
• ACCESS-CM3 Builder #168
• Realm extraction from file attributes #482
• Frequency metadata within files - decoupling filename dependence #507