2100 2726 2752 slicer bugfixes

[jack-rooks]

Description

Fixes slicer related bugs previously reported

For #2100:

• Adds the updateSlicer function in Plotter2D.py (primarily affects theoretical 2D data)

For #2726:

• Changes alpha (which was likely an angle) to theta in SectorSlicer.py

For #2752:

• Removes the group_id property from the plots as it functionally a duplicate of id. This change also eliminated the incorrect group_id in SectorSlicer.py that caused it to identify as the circular average
• Adds type_id which for all slicers is set to "Slicer" + name of the 2D data. This is used with an addition to setSlicer in Plotter2D.py to identify old slicer plots and remove them from the list. This will not remove the plot window, but will prevent it from reappearing if closed and the 2D data is replotted (primarily affects theoretical 2D data)

Fixes # (issue/issues)

How Has This Been Tested?

Tested on Windows 10

Review Checklist (please remove items if they don't apply):

• Code has been reviewed
• Functionality has been tested
• Windows installer (GH artifact) has been tested (installed and worked)
• MacOSX installer (GH artifact) has been tested (installed and worked)
• Developers documentation is available and complete (if required)
• The introduced changes comply with SasView license (BSD 3-Clause)

[jack-rooks]

Talked with @butlerpd, merging now since it addresses some issues raised in Slicer extension 1344