releng: add New-TerminalStackedChangelog (microsoft#11065)

I've done this process enough times that I should have written a script
to do it a while ago. This one is rough, but the whole changelog process
is pretty rough.

This script takes multiple revision ranges and produces something that
looks like a rough untranslated changelog, with indicators for how many
of the provided ranges had the same change (deduplicated by title.)

I use a process like this to build the Stable and Preview release notes
out of a set of revision ranges.

.github/actions/spelling/allow/allow.txt

@@ -1,6 +1,7 @@
 apc
 calt
 ccmp
+changelog
 cybersecurity
 Apc
 clickable
@@ -41,6 +42,7 @@ Lorigin
 maxed
 mkmk
 mru
+noreply
 nje
 ogonek
 ok'd

.github/actions/spelling/allow/names.txt

@@ -53,6 +53,7 @@ oldnewthing
 opengl
 osgwiki
 pabhojwa
+panos
 paulcam
 pauldotknopf
 PGP

tools/ReleaseEngineering/New-TerminalStackedChangelog.ps1

@@ -0,0 +1,82 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+#################################
+# New-TerminalStackedChangelog generates a markdown file with attribution
+# over a set of revision ranges.
+# Dustin uses it when he's writing the changelog.
+# 
+## For example, generating the changelog for both 1.9 and 1.10 might look like this:
+# $ New-TerminalStackedChangelog 1.9..release-1.9, 1.10..release-1.10
+## The output will be a markdown-like document. Each commit will be converted into a
+## single-line entry with attribution and an optional count:
+#
+# * Foo the bar (thanks @PanosP!)
+# * [2] Fix the bug
+#
+# Entries with a count were present in both changelists.
+#
+# If you don't have the release tags/branches checked out locally, you might
+# need to do something like:
+#
+# $ New-TerminalStackedChangelog origin/release-1.8..origin/release-1.9
+
+[CmdletBinding()]
+Param(
+    [string[]]$RevisionRanges
+)
+
+Function Test-MicrosoftPerson($email) {
+    Return $email -like "*@microsoft.com" -Or $email -like "pankaj.d*"
+}
+
+Function Generate-Thanks($Entry) {
+    # We don't need to thank ourselves for doing our jobs
+    If ($_.Microsoft) {
+        ""
+    } ElseIf (-Not [string]::IsNullOrEmpty($_.PossibleUsername)) {
+        " (thanks @{0}!)" -f $_.PossibleUsername
+    } Else {
+        " (thanks @<{0}>!)" -f $_.Email
+    }
+}
+
+$usernameRegex = [regex]::new("(?:\d+\+)?(?<name>[^@]+)@users.noreply.github.com")
+Function Get-PossibleUserName($email) {
+    $match = $usernameRegex.Match($email)
+    if ($null -Ne $match) {
+        return $match.Groups["name"].Value
+    }
+    return $null
+}
+
+$Entries = @()
+
+ForEach ($RevisionRange in $RevisionRanges) {
+    # --pretty=format notes:
+    #   - %an: author name
+    #   - %x1C: print a literal FS (0x1C), which will be used as a delimiter
+    #   - %ae: author email
+    #   - %x1C: another FS
+    #   - %s: subject, the title of the commit
+    $NewEntries = & git log $RevisionRange "--pretty=format:%an%x1C%ae%x1C%s" |
+        ConvertFrom-CSV -Delimiter "`u{001C}" -Header Author,Email,Subject
+
+    $Entries += $NewEntries | % { [PSCustomObject]@{
+        Author = $_.Author;
+        Email = $_.Email;
+        Subject = $_.Subject;
+        Microsoft = (Test-MicrosoftPerson $_.Email);
+        PossibleUsername = (Get-PossibleUserName $_.Email);
+    } }
+}
+
+$Unique = $Entries | Group-Object Subject | %{ $_.Group[0] | Add-Member Count $_.Count -Force -PassThru }
+
+$Unique | % {
+    $c = ""
+    If ($_.Count -Gt 1) {
+        $c = "[{0}] " -f $_.Count
+    }
+    "* {0}{1}{2}" -f ($c, $_.Subject, (Generate-Thanks $_))
+}