PR Summary

Allows user to configure prompt colors (e.g. when removing non-empty directories or explicitly giving-Confirm flag). The configurable colors and the default values are as following (up to discussion):

• Caption - bold yellow, same as warnings
• Message - default (reset)
• Help - default (reset)
• Choice selected by default - white on blue
• Choice not selected by default - blue
• Choice for help - default (reset)

Changes in resource strings to avoid coloring trailing whitespace, which leads to visual artifacts for background colors.

Test had to be written by forking the powershell executable, as I could find no other way to both allow interactive prompt (disqualifies[System.Management.Automation.PowerShell] even with test hooks) and capture output fromWrite(Line)ToConsole (disqualifies regular invocation, even with test hooks). Test is tagged slow because it takes up to 100 times longer than similar tests using[System.Management.Automation.PowerShell] (80ms vs 8s), but if this method is too janky to use in CI, I can simply remove it and mark PR as "can only be tested interactively".

Closes#17961

PR Context

Existing colors are hardcoded and are either yellow+white when on light background, or blue+black on white background. Because it is not really possible to reliably detect background colors, especially considering remoting over PSSession or ssh, or embedding sessions in screen or tmux, this leads to white text on white background, completely invisible.

Without PR:

With PR (defaults):

With PR (custom):

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
• [xv This PR is ready to merge and is notWork in Progress.
  • If the PR is work in progress, please add the prefixWIP: or[ WIP ] to the beginning of the title (theWIP bot will keep its status check atPending while the prefix is present) and remove the prefix when the PR is ready.
• Breaking changes
  • None
  • OR
  • Experimental feature(s) needed
    • Experimental feature name(s):
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed:Make prompt colors configurable MicrosoftDocs/PowerShell-Docs#10339
• 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 opened an issue in the relevant tool repository. This may include:
    • Impact onPowerShell Editor Services which is used in thePowerShell extension for VSCode
      (which runs in a different PS Host).
      • Issue filed:
    • Impact on Completions (both in the console and in editors) - one of PowerShell's most powerful features.
      • Issue filed:
    • Impact onPSScriptAnalyzer (which provides linting & formatting in the editor extensions).
      • Issue filed:
    • Impact onEditorSyntax (which provides syntax highlighting with in VSCode, GitHub, and many other editors).
      • Issue filed: