Add unit test case for DataGridView 16 events

[John-Qiao]

related https://github.com/dotnet/winforms/issues/10453

Proposed changes

• Add unit tests for below 16 events

1. ColumnHeadersBorderStyleChanged
2. ColumnHeadersDefaultCellStyleChanged
3. DataMemberChanged
4. DataSourceChanged
5. DefaultCellStyleChanged
6. EditModeChanged
7. GridColorChanged
8. MultiSelectChanged
9. ReadOnlyChanged
10. RowHeadersBorderStyleChanged
11. RowHeadersDefaultCellStyleChanged
12. RowsDefaultCellStyleChanged
13. CurrentCellChanged
14. CurrentCellDirtyStateChanged
15. SelectionChanged
16. Sorted

Microsoft Reviewers: Open in CodeFlow

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 74.50645%. Comparing base (566bec4) to head (7d0a6ca).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #11556 +/- ## =================================================== + Coverage 74.48439% 74.50645% +0.02205% =================================================== Files 3039 3039 Lines 629066 629324 +258 Branches 46834 46834 =================================================== + Hits 468556 468887 +331 + Misses 157154 157063 -91 - Partials 3356 3374 +18 ``` | [Flag](https://app.codecov.io/gh/dotnet/winforms/pull/11556/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | Coverage Δ | | |---|---|---| | [Debug](https://app.codecov.io/gh/dotnet/winforms/pull/11556/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `74.50645% <100.00000%> (+0.02205%)` | :arrow_up: | | [integration](https://app.codecov.io/gh/dotnet/winforms/pull/11556/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `17.88990% <ø> (-0.08859%)` | :arrow_down: | | [production](https://app.codecov.io/gh/dotnet/winforms/pull/11556/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `47.37462% <ø> (+0.02631%)` | :arrow_up: | | [test](https://app.codecov.io/gh/dotnet/winforms/pull/11556/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `96.97293% <100.00000%> (+0.00169%)` | :arrow_up: | | [unit](https://app.codecov.io/gh/dotnet/winforms/pull/11556/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `44.50334% <ø> (+0.16523%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#carryforward-flags-in-the-pull-request-comment) to find out more.