Add snippets for debug configurations

[matthewbastien]

Add three new Swift debug configuration snippets:

• Launch process
• Attach by process name
• Attach by process ID

Also, added a process picker command that can be used to select a process to attach to. The logic is largely the same as the process picker in the vscode-js-debug extension created by Microsoft. It will use available executables based on the current platform to find the list of available processes:

• Linux: uses the ps executable to list processes
• macOS: nearly identical to Linux except that the command line options passed to ps are different
• Windows: uses the PowerShell cmdlet Get-CimInstance to query for processes

I manually tested this on a MacBook Pro running macOS Sequoia, a Windows 11 VM, and an Ubuntu 22.04 VM.

[plemarquand]

Verification depends on #1464

[plemarquand]

Verified in a1a6b0f