Add ServicingPipeline.ps1, a script I use to service Terminal (#12789)

This script takes pull requests from a project board, cherry-picks them,
and updates the project board. It also yells at you if there are
conflicts to resolve, and generally tries to keep track of everything.
It is quite cool.

.github/actions/spelling/excludes.txt

@@ -76,6 +76,7 @@ SUMS$
 ^src/tools/texttests/fira\.txt$
 ^src/tools/U8U16Test/(?:fr|ru|zh)\.txt$
 ^src/types/ut_types/UtilsTests.cpp$
+^tools/ReleaseEngineering/ServicingPipeline.ps1$
 ^\.github/actions/spelling/
 ^\.gitignore$
 ^\XamlStyler.json$

tools/ReleaseEngineering/ServicingPipeline.ps1

@@ -0,0 +1,127 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+#Requires -Version 7
+#Requires -Modules PSGitHub
+
+[CmdletBinding()]
+Param(
+    [string]$Version,
+    [string]$SourceBranch = "origin/main",
+    [switch]$GpgSign = $False
+)
+
+Function Prompt() {
+    "PSCR {0}> " -f $PWD.Path
+}
+
+Function Enter-ConflictResolutionShell($entry) {
+    $Global:Abort = $False
+    $Global:Skip = $False
+    $Global:Reject = $False
+    Push-Location -StackName:"ServicingStack" -Path:$PWD > $Null
+    Write-Host (@"
+`e[31;1;7mCONFLICT RESOLUTION REQUIRED`e[m
+`e[1mCommit `e[m: `e[1;93m{0}`e[m
+`e[1mSubject`e[m: `e[1;93m{1}`e[m
+
+"@ -f ($_.CommitID, $_.Subject))
+
+    & git status --short
+
+    Write-Host (@"
+
+`e[1mCommands`e[m
+`e[1;96mdone  `e[m Complete conflict resolution and commit
+`e[1;96mskip  `e[m Skip this commit
+`e[1;96mabort `e[m Stop everything
+`e[1;96mreject`e[m Skip and `e[31mremove this commit from servicing consideration`e[m
+"@)
+    $Host.EnterNestedPrompt()
+    Pop-Location -StackName:"ServicingStack" > $Null
+}
+
+Function Done() {
+    $Host.ExitNestedPrompt()
+}
+
+Function Abort() {
+    $Global:Abort = $True
+    $Host.ExitNestedPrompt()
+}
+
+Function Skip() {
+    $Global:Skip = $True
+    $Host.ExitNestedPrompt()
+}
+
+Function Reject() {
+    $Global:Skip = $True
+    $Global:Reject = $True
+    $Host.ExitNestedPrompt()
+}
+
+$Script:TodoColumnName = "To Cherry Pick"
+$Script:DoneColumnName = "Cherry Picked"
+$Script:RejectColumnName = "Rejected"
+
+# Propagate default values into all PSGitHub cmdlets
+$PSDefaultParameterValues['*GitHub*:Owner'] = "microsoft"
+$PSDefaultParameterValues['*GitHub*:RepositoryName'] = "terminal"
+
+$Project = Get-GithubProject -Name "$Version Servicing Pipeline"
+$AllColumns = Get-GithubProjectColumn -ProjectId $Project.id
+$ToPickColumn = $AllColumns | ? Name -Eq $script:TodoColumnName
+$DoneColumn = $AllColumns | ? Name -Eq $script:DoneColumnName
+$RejectColumn = $AllColumns | ? Name -Eq $script:RejectColumnName
+$Cards = Get-GithubProjectCard -ColumnId $ToPickColumn.id
+
+& git fetch --all 2>&1 | Out-Null
+
+$Entries = @(& git log $SourceBranch --grep "(#\($($Cards.Number -Join "\|")\))" "--pretty=format:%H%x1C%s"  |
+    ConvertFrom-CSV -Delimiter "`u{001C}" -Header CommitID,Subject)
+
+[Array]::Reverse($Entries)
+
+$PickArgs = @()
+If ($GpgSign) {
+    $PickArgs += , "-S"
+}
+
+$CommitPRRegex = [Regex]"\(#(\d+)\)$"
+$Entries | ForEach-Object {
+    Write-Host "`e[96m`e[1;7mPICK`e[22;27m $($_.CommitID): $($_.Subject)`e[m"
+    $PR = $CommitPRRegex.Match($_.Subject).Groups[1].Value
+    $Card = $Cards | ? Number -Eq $PR
+    $null = & git cherry-pick -x $_.CommitID 2>&1
+    $Err = ""
+    While ($True) {
+        If ($LASTEXITCODE -ne 0) {
+            $Err
+            Enter-ConflictResolutionShell $_
+
+            If ($Global:Abort) {
+                & git cherry-pick --abort
+                Write-Host -ForegroundColor "Red" "YOU'RE ON YOUR OWN"
+                Exit
+            }
+
+            If ($Global:Reject) {
+                Move-GithubProjectCard -CardId $Card.id -ColumnId $RejectColumn.id
+                # Fall through to Skip
+            }
+
+            If ($Global:Skip) {
+                & git cherry-pick --skip
+                Break
+            }
+
+            $Err = & git cherry-pick --continue --no-edit
+        } Else {
+            & git commit @PickArgs --amend --no-edit --trailer "Service-Card-Id:$($Card.Id)" --trailer "Service-Version:$Version" | Out-Null
+            Write-Host "`e[92;1;7m OK `e[m"
+            Move-GithubProjectCard -CardId $Card.id -ColumnId $DoneColumn.id
+            Break
+        }
+    }
+}