Improve package structure

[data4knowledge]

Separate out the Excel processing from the processing of the USDM data.

• The Excel processing should be focused on the work necessary to turn the Excel content into a USDM object tree (Wrapper and Study down), most of the existing code
• A separate piece that turns the USDM object tree into HTML, JSON, PDF ...
• Also need to improve the Study sheet processing. Currently performing two roles:
  • Reading the sheet
  • Building the whole USDM object tree
• Improve the 'global' classes, identifier manager, error logging etc. They are currently global and stop the package being used in a threaded environment.

[data4knowledge]

Included within this issue as some of the work overlaps and efficient.

• Start tidying up the error handling including the sheet general exception
• Add section handling for timeline rather than whole SoA
• Fix and improve address handling

[data4knowledge]

Merged into main