Update to WinAppSDK 1.7 latest version (#39016)

* Update to WinAppSDK 1.7 latest version
* Update UpdateVersions.ps1

Signed-off-by: Shawn Yuan <shuai.yuan.zju@gmail.com>
Co-authored-by: Dustin L. Howett <dustin@howett.net>
Co-authored-by: Shawn Yuan <128874481+shuaiyuanxx@users.noreply.github.com>
Co-authored-by: Shawn Yuan <shuai.yuan.zju@gmail.com>
Co-authored-by: Clint Rutkas <clint@rutkas.com>

.pipelines/v2/ci-using-the-latest-winappsdk.yml

@@ -33,7 +33,7 @@ parameters:
     default: true
   - name: winAppSDKVersionNumber
     type: string
-    default: 1.6
+    default: 1.7
   - name: useExperimentalVersion
     type: boolean
     default: false

.pipelines/v2/templates/steps-update-winappsdk-and-restore-nuget.yml

@@ -17,6 +17,7 @@ steps:
     arguments: >
       -winAppSdkVersionNumber ${{ parameters.versionNumber }}
       -useExperimentalVersion $${{ parameters.useExperimentalVersion }}
+      -rootPath "$(build.sourcesdirectory)"
 
 - script: echo $(WinAppSDKVersion)
   displayName: 'Display WinAppSDK Version Found'