undo_redo branch rebased to refactor_24

[rozyczko]

Description

This PR adds fine-grained undo-redo functionality to the fitting perspective.
The undo stack is created per fit page, allowing each page to be treated separately.

Note: fitting undo has NOT yet been implemented, hence the draft mode

Review Checklist:

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Documentation (check at least one)

• There is nothing that needs documenting
• Documentation changes are in this PR
• There is an issue open for the documentation (link?)
• The documentation will be added later

Installers

• There is a chance this will affect the installers, if so
  • Windows installer (GH artifact) has been tested (installed and worked)
  • MacOSX installer (GH artifact) has been tested (installed and worked)
  • Wheels installer (GH artifact) has been tested (installed and worked)

Licensing (untick if necessary)

• The introduced changes comply with SasView license (BSD 3-Clause)