Net FX 48 Accessibility Fixes port

[M-Lipin]

Porting accessibility fixes for DataGridView, ToolStrip and PropertyGrid controls.

contributes to #182

[dnfclas]

All CLA requirements met.

[zsd4yr]

@M-Lipin is this ready for code review? Could you resolve the CLA check?

@Tanya-Solyanik once this is ready, will you be the one to review these changes?

[Tanya-Solyanik]

@M-Lipin - Looks reasonable, could you please describe how you diff'ed and tested this change? Looking at the change, I'm pretty sure you did not override anything new in Core, but did you get everything from the "desktop"?

[M-Lipin]

@Tanya-Solyanik - I diffed all the fixes from "desktop" (which are implemented after introducing WinForms to .NET Core) one by one with the Core source code. Basically I took the fix changeset that went to NetFXDev1, diffed all the changes, merged to Core and saved the corresponding Core files. Then I took the next bug changeset (in time order: firstly I took the oldest changeset, then the newer one) and incremented or overwrote the changes (if there were newer changes in the same files and same code lines).

I tested the changes by creating the test Core WinForms application with all updated controls: ComboBox, DataGridView, PropertyGrid and performed some basic tests: UI works as expected, accessibility fixes (tested in Inspect and Narrator) are presented in Core WinForms app.

There is nothing new in Core in comparison with "desktop", all the accessibility fixes that I implemented earlier should be in this port.

[zsd4yr]

@M-Lipin looks like there is a build error in the PR. Please take a look by clicking on Details down here next to the dotnet-winforms CI check, then View more details on Azure Pipelines on the bottom of the resulting page. (direct link). Click on either Job (Debug or Release) and then click on the build step to see the log and error.

Looks like there is an issue with SR files being out of sync and that you need to run msbuild /t:UpdateXlf locally and push again to resolve.