Expose default PowerShell User-Agent in Microsoft.PowerShell.Commands.PSUserAgent

[Christophoclese]

Summary of the new feature / enhancement

As a developer of a client library that makes use of Invoke-WebRequest, I would like to be able to easily extend the default User-Agent header that is sent. The Microsoft.PowerShell.Commands.PSUserAgent class provides public static strings for various common user agents, but doesn't expose its own.

After some searching I was able to find a mention of a way to access the private class member, but I'm not sure I would have been able to work this out on my own:

PS /home/cbarton> [Microsoft.PowerShell.Commands.PSUserAgent].GetMembers('Static, NonPublic').Where{$_.Name -eq 'UserAgent'}.GetValue($null,$null)
Mozilla/5.0 (Linux; Ubuntu 20.04.6 LTS; ) PowerShell/7.4.1

This would be potentially more understandable and discoverable if it were exposed in the same way as the other user agents, e.g:

PS /home/cbarton> [Microsoft.PowerShell.Commands.PSUserAgent]::PowerShell
Mozilla/5.0 (Linux; Ubuntu 20.04.6 LTS; ) PowerShell/7.4.1

The end goal was to be able to do something like this:

$CustomUserAgent = [Microsoft.PowerShell.Commands.PSUserAgent]::PowerShell + " foo/x.x.x"
Invoke-WebRequest -Uri 'https://httpbin.org/headers' -UserAgent $CustomUserAgent

Proposed technical implementation details (optional)

I believe the relevant file is here. I'm not a c# developer but guessing this would go something like this:

        /// <summary>
        /// Useragent string for PowerShell (Current Version).
        /// </summary>
        public static string PowerShell => UserAgent;