FieldWorks: Test using the designer with VS 2019 16.8

[tombogle]

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[tombogle]

@ermshiperete, which branch should this be done on, or does it not matter? I'm not yet seeing any extra csproj files that were added to work with Designer.

[tombogle]

I have managed to get 7 projects to build. Can't get most of the solution to build because of this error:
1>IDL Import threw an exception: An entry with the same key already exists.
1>C:\Projects\FieldWorks\Src\ViewsInterfaces\ViewsInterfaces.csproj(54,5): error MSB4181: The "IdlImp" task returned false but did not log an error.
1>Done building project "ViewsInterfaces.csproj" -- FAILED.
I have successfully opened several controls and dialogs in FwCoreDlgs using Designer.
Some that fail include:
ComboTextBox (The base class 'SIL.FieldWorks.FwCoreDlgs.Controls.InnerFwTextBox' could not be loaded)
DefaultFontsControl (Could not find type 'SIL.FieldWorks.FwCoreDlgs.FwOverrideComboBox')
InnerFwTextBox (The base class 'SIL.FieldWorks.Common.RootSites.SimpleRootSite' could not be loaded.)
AddCnvrtrDlg (Could not find type 'SIL.FieldWorks.FwCoreDlgs.CnvtrPropertiesCtrl)
CharContextCtrl (Could not find type 'SIL.FieldWorks.FwCoreDlgs.FwPanel'.)
FwWritingSystemSetupDlg (The designer loader did not provide a root component but has not indicated why.)

Probably not worth trying to go any further unless/until I can figure out how to get everything to build.

[tombogle]

All the controls in the Controls folder now open correctly in Designer. However, the last three items in the above list still fail.

[tombogle]

After changing several properties in FwPanel/FwTextPanel to either be non-browsable and hidden in Designer or making them public instead of internal, I was able to open CharContextCtrl in Designer.