PR Summary

• Adds an experimental flag called "Microsoft.PowerShell.Utility.PSManageBreakpointsInRunspace". All experimental functionality described below is enabled/disabled using that flag.
• Removes the recently added New-PSBreakpoint experimental cmdlet. This functionality is provided via SDK commands for now, and will be provided via a -Runspace parameter on *-PSBreakpoint commands in a PR once this one is finalized.
• Adds SetCommandBreakpoint, SetVariableBreakpoint, SetLineBreakpoint, EnableBreakpoint, DisableBreakpoint, and RemoveBreakpoint public APIs to the Debugger class, plumbs them through the engine, and hooks them up for remote debugger work. Also hooks up the GetBreakpoint, GetBreakpoints, and SetBreakpoints Debugger class APIs for remote debugger work.
• Adds a -NoInitialBreak experimental parameter to Debug-Runspace and Debug-Job that allows users to attach the debugger without invoking a BreakAll. The corresponding methods for the same have boolean parameters allowing this as well.
• Hooks up Set-PSBreakpoint to the new debugger APIs that have superceded the ones it used to use.

PR Context

This PR is needed for "attach to process" debugging in PowerShell Editor Services.

It helps because:

• It allows scripters to fully manage breakpoints in a remote runspace without having to use Debug-* to attach the debugger to that runspace.
• It allows Tyler to attach a debugger to a runspace without invoking a BreakAll in PSES.

Important details about this PR:

1. It does not include Pester tests for the -NoInitialBreak parameter added to Debug-Runspace and Debug-Job, nor does it include Pester tests for the corresponding boolean value in the DebugRunspace and DebugJob APIs. I'm not sure how to automate that test, and believe it should be tested manually. Fortunately, that is an easy manual test to take on.
2. The tests in the new Breakpoint.Tests.ps1 file sometimes hang. I don't know why this happens. It has to do with working with a remote runspace and using the breakpoint APIs against it. It doesn't happen all the time, but it happens often. After 30 minutes, it will time out and fail. I need help identifying why this happens, by someone who understands the MS-PSRDP better than I do.

cc: @TylerLeonhardt @PaulHigin @SteveL-MSFT

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: or [ WIP ] to the beginning of the title (the WIP bot will keep its status check at Pending while the prefix is present) and remove the prefix when the PR is ready.
• Breaking changes
  • None
  • OR
  • Some (experimental features are required if breaking changes are included).
• Experimental features
  • Experimental feature(s) needed
    • Experimental feature name(s): Microsoft.PowerShell.Utility.PSManageBreakpointsInRunspace
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed:
• Testing - New and feature
  • N/A or can only be tested interactively
  • OR
  • Make sure you've added a new test if existing tests do not effectively test the code changed
• Tooling
  • I have considered the user experience from a tooling perspective and don't believe tooling will be impacted.
  • OR
  • I have considered the user experience from a tooling perspective and enumerated concerns in the summary. This may include:
    • Impact on PowerShell Editor Services which is used in the PowerShell extension for VSCode (which runs in a different PS Host).
    • Impact on Completions (both in the console and in editors) - one of PowerShell's most powerful features.
    • Impact on PSScriptAnalyzer (which provides linting & formatting in the editor extensions).
    • Impact on EditorSyntax (which provides syntax highlighting with in VSCode, GitHub, and many other editors).