Add markdown table formatting when copying stacks for GitHub issues

[Copilot]

When copying and pasting stacks from PerfView into a GitHub issue, most lines start with + which GitHub interprets as bulleted list items instead of being part of the same table. This causes the pasted data to render incorrectly.

This PR modifies the clipboard formatting to add:

1. A leading | character to the first column of each row
2. A trailing | character to the last column of each row

With these changes, GitHub correctly renders the pasted content as a markdown table rather than as a bulleted list.

The changes are minimal and focused on the clipboard formatting functionality in the CopyingRowClipboardContent event handler within PerfDataGrid.xaml.cs. The implementation preserves existing functionality like content compression and column padding while ensuring consistent formatting across header rows and data rows.

Fixes #940.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• crl3.digicert.com
  • Triggering command: dotnet build (dns block)
• crl4.digicert.com
  • Triggering command: dotnet build (dns block)
• ocsp.digicert.com
  • Triggering command: dotnet build (dns block)
• s.symcb.com
  • Triggering command: dotnet build (dns block)
• s.symcd.com
  • Triggering command: dotnet build (dns block)
• ts-crl.ws.symantec.com
  • Triggering command: dotnet build (dns block)
• ts-ocsp.ws.symantec.com
  • Triggering command: dotnet build (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[brianrob]

With this change, copy and paste from a stack view looks like this:

| Name                                                                                                                                                                 	 Inc %	      Inc |
|  ROOT                                                                                                                                                                	 100.0	   65,823 |
| + Process64 ServiceHub.RoslynCodeAnalysisService (39312) Args:  dotnet$RoslynCodeAnalysisService net.pipe://45084D8CB57FA7939F2FFB7CB0AF143CCCBE0 "/TelemetrySession:	 100.0	   65,823 |
|  + Thread (51700) CPU=1813ms (.NET IO ThreadPool Worker)                                                                                                             	   2.8	    1,813 |
|  |+ module ntdll <<ntdll!?>>                                                                                                                                         	   2.7	    1,757 |
|  ||+ module kernel32 <<kernel32!?>>                                                                                                                                  	   2.7	    1,757 |
|  || + module coreclr <<coreclr!?>>                                                                                                                                   	   2.7	    1,757 |
|  ||  + module  <<?!?>>                                                                                                                                               	   2.7	    1,757 |

What do you think @AArnott (Better late than never)?

[AArnott]

Great. I love seeing how Copilot can increase capacity to get github issues resolved too. What a treat.

[brianrob]

Great. I love seeing how Copilot can increase capacity to get github issues resolved too. What a treat.

Yup! Expect to see a whole lot more of that.