Remove duplicate DpiHelper implementation

[hughbe]

Closes #2120

Proposed Changes

• First we need to consolidate the various Interop functions (GetProcessDpiAwareness, SetProcessDpiAwareness, IsValidDpiAwarenessContext, SetProcessDpiAwarenessContext, IsProcessDPIAware and SetProcessDPIAware) allowing us to use the common file
• Then include the common file in System.Windows.Forms.Design.Editors.csproj
• Include the function ScaleButtonImageLogicalToDevice in the common file

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Merging #2131 into master will decrease coverage by 0.03577%.
The diff coverage is 5.12821%.

@@                 Coverage Diff                 @@
##              master       #2131         +/-   ##
===================================================
- Coverage   29.12306%   29.08728%   -0.03578%     
===================================================
  Files            940         939          -1     
  Lines         266665      266577         -88     
  Branches       37946       37937          -9     
===================================================
- Hits           77661       77540        -121     
- Misses        183787      183818         +31     
- Partials        5217        5219          +2

Flag	Coverage Δ
#Debug	29.08728% <5.12821%> (-0.03578%)	⬇️
#production	29.08728% <5.12821%> (-0.03578%)	⬇️
#test	100% <ø> (ø)	⬆️

[merriemcgaw]

This could have some significant impact if not done perfectly to the layout and behavior of controls. Please do some UI validations and ensure that things appear OK on secondary monitors, and that there's no behavior changes when dragging a form with many controls from one monitor to the next. That isn't working great, but we don't want to to regress further.

[zsd4yr]

@dreddy-work should definitely look at this

[RussKie]

LGTM

[hughbe]

This could have some significant impact if not done perfectly to the layout and behavior of controls. Please do some UI validations and ensure that things appear OK on secondary monitors, and that there's no behavior changes when dragging a form with many controls from one monitor to the next. That isn't working great, but we don't want to to regress further.

I'm not really able to do this at the moment as I only have a mac and a windows VM. Any suggestions for secondary monitor testing? I wouldn't expect any regressions as this is simply cleaning up interop then removing a duplicate file. That said, I am willing to be proved wrong :D

[gpetrou]

Perhaps remove CommonUnsafeNativeMethodsTests.cs or move/enable the commented tests with this PR?

[hughbe]

Yeah. smart

[JeremyKuhne]

Thanks! The existing interop methods weren't using the right data type for DPI_AWARENESS_CONTEXT. I swear I wrote this up at some point, but it might have been in the internal temporary Git repository when this project was just starting. Ugh. :)

[RussKie]

@JeremyKuhne it is all yours :)

@dreddy-work it would be great if you had a look too.

[dreddy-work]

Change functionally look good to me.