Filings UI: refactor Todo List (cont)

[severinbeauvais]

Description:

The Todo List is overly complicated due to many different scenarios and special cases. The problems with this are:

• difficult to understand code, and difficult to add new scenarios
• difficult to verify (and to write unit tests - see todo list tweaks and prep for further unit tests business-filings-ui#176)
• high probability of breaking some scenarios when changing anything
• not all scenarios are currently being verified by unit tests

In #5802, some effort was made to characterize this problem and create a new unit test file to cover all scenarios... but this got very complicated as well. Hence, THIS ticket was created.

To do:

• refactor Todo List to simplify the scenarios (eg, big sections for each task state, and special cases within those?)
  • partly done in Filings UI: refactor Todo List #6168
• implement the new unit tests -- by state and special case (or however it was decided to reorg the scenarios)
  • partly done in Filings UI: refactor Todo List #6168

[severinbeauvais]

Some cleanup has already been committed to main branch (in #6168).

There is outstanding work in this branch/PR: bcgov/business-filings-ui#390

THIS ticket should complete the above work.