Add a Third-Party notices link to the about dialog (#5508)

## Summary of the Pull Request
This PR will add a link to the version of `NOTICE.md` in GitHub at the commit that the build was on. It uses the same approach for generating our settings files, where we'll create a header file with the commit hash assigned to a `wstring_view` during build time.

<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist
* [x] Closes #5139
* [x] CLA signed.
* [x] Tests added/passed

<!-- Describe how you validated the behavior. Add automated tests wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed
The link is there and goes to the expected `NOTICE.md`.

src/cascadia/TerminalApp/Resources/en-US/Resources.resw

@@ -273,6 +273,10 @@
     <value>Privacy Policy</value>
     <comment>A hyperlink name for the Terminal's privacy policy</comment>
   </data>
+  <data name="AboutDialog_ThirdPartyNoticesLink.Content" xml:space="preserve">
+    <value>Third-Party Notices</value>
+    <comment>A hyperlink name for the Terminal's third-party notices</comment>
+  </data>
   <data name="ApplicationDisplayNameUnpackaged" xml:space="preserve">
     <value>Windows Terminal (Unpackaged)</value>
     <comment>This display name is used when the application's name cannot be determined</comment>

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -18,6 +18,8 @@
 #include "TabRowControl.h"
 #include "DebugTapConnection.h"
 
+#include "CurrentCommitHash.h" // For the about dialog's ThirdPartyNotices link
+
 using namespace winrt;
 using namespace winrt::Windows::Foundation::Collections;
 using namespace winrt::Windows::UI::Xaml;
@@ -254,6 +256,12 @@ namespace winrt::TerminalApp::implementation
         return RS_(L"ApplicationVersionUnknown");
     }
 
+    winrt::hstring TerminalPage::ThirdPartyNoticesLink()
+    {
+        winrt::hstring link{ fmt::format(L"https://github.com/microsoft/terminal/blob/{}/NOTICE.md", CurrentCommitHash) };
+        return link;
+    }
+
     // Method Description:
     // - Displays a dialog for warnings found while closing the terminal app using
     //   key binding with multiple tabs opened. Display messages to warn user

src/cascadia/TerminalApp/TerminalPage.h

@@ -45,6 +45,8 @@ namespace winrt::TerminalApp::implementation
         winrt::hstring ApplicationDisplayName();
         winrt::hstring ApplicationVersion();
 
+        winrt::hstring ThirdPartyNoticesLink();
+
         void CloseWindow();
 
         int32_t SetStartupCommandline(winrt::array_view<const hstring> args);

src/cascadia/TerminalApp/TerminalPage.idl

@@ -17,6 +17,8 @@ namespace TerminalApp
         String ApplicationDisplayName { get; };
         String ApplicationVersion { get; };
 
+        String ThirdPartyNoticesLink { get; };
+
         event Windows.Foundation.TypedEventHandler<Object, String> TitleChanged;
         event Windows.Foundation.TypedEventHandler<Object, LastTabClosedEventArgs> LastTabClosed;
         event Windows.Foundation.TypedEventHandler<Object, Windows.UI.Xaml.UIElement> SetTitleBarContent;

src/cascadia/TerminalApp/TerminalPage.xaml

@@ -43,6 +43,9 @@ the MIT License. See LICENSE in the project root for license information. -->
                 <HyperlinkButton
                     x:Uid="AboutDialog_PrivacyPolicyLink"
                     NavigateUri="https://go.microsoft.com/fwlink/?linkid=2125418" />
+                <HyperlinkButton
+                    x:Uid="AboutDialog_ThirdPartyNoticesLink"
+                    NavigateUri="{x:Bind ThirdPartyNoticesLink}" />
             </StackPanel>
         </ContentDialog>
 

src/cascadia/TerminalApp/lib/TerminalAppLib.vcxproj

@@ -330,4 +330,8 @@
   <Target Name="_TerminalAppGenerateUserSettingsH" Inputs="..\userDefaults.json" Outputs="Generated Files\userDefaults.h" BeforeTargets="BeforeClCompile">
     <Exec Command="powershell.exe -noprofile –ExecutionPolicy Unrestricted $(OpenConsoleDir)\tools\GenerateHeaderForJson.ps1 -JsonFile ..\userDefaults.json -OutPath '&quot;Generated Files\userDefaults.h&quot;' -VariableName UserSettingsJson" />
   </Target>
+  <!-- Get the hash of the current git commit this build is on.-->
+  <Target Name="_GenerateCurrentCommitHashH" Inputs="..\..\..\..\NOTICE.md;..\..\..\..\tools\GenerateCommitHashHeader.ps1" Outputs="Generated Files\CurrentCommitHash.h" BeforeTargets="BeforeClCompile">
+    <Exec Command="powershell.exe -noprofile -ExecutionPolicy Unrestricted $(OpenConsoleDir)\tools\GenerateCommitHashHeader.ps1" />
+  </Target>
 </Project>

tools/GenerateCommitHashHeader.ps1

@@ -0,0 +1,21 @@
+# This script gets the current git commit hash and places it in a header file stamped to a wstring_view
+# If we're unable to retrieve the hash, we'll return the hard coded string "master" instead.
+
+$filePath = "Generated Files\CurrentCommitHash.h"
+
+Write-Output "constexpr std::wstring_view CurrentCommitHash{ L`"" | Out-File -FilePath $filePath -Encoding ASCII -NoNewline
+
+# Let's see if we're on a build agent that can give us the commit hash through this predefined variable.
+$hash = $env:Build_SourceVersion
+if (-not $hash)
+{
+    # Otherwise attempt to invoke git to get the commit.
+    $hash = git rev-parse HEAD
+    if ($LASTEXITCODE -or -not $hash)
+    {
+        $hash = "master"
+    }
+}
+
+$hash | Out-File -FilePath $filePath -Encoding ASCII -Append -NoNewline
+Write-Output "`" };" | Out-File -FilePath $filePath -Encoding ASCII -Append -NoNewline