Fix setMarkerStyle

[searscr]

Description of work

This PR is to fix a typo from MatrixWorkspace.getMarkerType() to MatrixWorkspace.getMarkerStyle().

Summary of work

In an effort to improve plotting Matrix workspaces as Marker workspaces a function was added to MatrixWorkspace to set the marker style per workspace. A typo had getMarkerType rather than the correct function call of getMarkerStyle. This PR is to fix that typo as well as include input validation for marker style and plot type.

Fixes Defect EWM 8982

This defect arose while testing #38548 an exception was observed when trying to test the required ability to set custom marker type per workspace. When doing this via:

ws = CreateSampleWorkspace()
ws.setPlotType('marker')
ws.setMarkerStyle('point')

and then attempting to right-click plot the workspace yields an exception:

AttributeError: 'Workspace2D' object has no attribute 'getMarkerType'

To test:

The above workflow should produce a plot without an exception.

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