Merged PR 37937: Fix Windows Signing stage and MSIX create stage

Fix Windows Signing stage and MSIX create stage

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#### AI description  (iteration 1)
#### PR Classification
Bug fix addressing issues in the Windows Signing and MSIX creation stages.

#### PR Summary
This pull request fixes the Windows signing and MSIX package creation processes. It ensures that dotnet is available early in the bootstrap and corrects YAML condition expressions for package tasks.
- `build.psm1`: Moved the dotnet availability check to an earlier section, ensuring that .NET SDK dependencies are met before proceeding.
- `.pipelines/templates/package-create-msix.yml`: Updated condition expressions to use variable dictionary references for both preview and stable/LTS package tasks.
<!-- GitOpsUserAgent=GitOps.Apps.Server.pullrequestcopilot -->

.pipelines/templates/package-create-msix.yml

@@ -240,7 +240,7 @@ jobs:
 
     - task: MS-RDX-MRO.windows-store-publish.package-task.store-package@3
       displayName: 'Create StoreBroker Package (Preview)'
-      condition: eq('$(PREVIEW)', 'true')
+      condition: eq(variables['PREVIEW'], 'true')
       inputs:
         serviceEndpoint: 'StoreAppPublish-Preview'
         sbConfigPath: '$(SBConfigPath)'
@@ -252,7 +252,7 @@ jobs:
 
     - task: MS-RDX-MRO.windows-store-publish.package-task.store-package@3
       displayName: 'Create StoreBroker Package (Stable/LTS)'
-      condition: or(eq('$(STABLE)', 'true'), eq('$(LTS)', 'true'))
+      condition: or(eq(variables['STABLE'], 'true'), eq(variables['LTS'], 'true'))
       inputs:
         serviceEndpoint: 'StoreAppPublish-Stable'
         sbConfigPath: '$(SBConfigPath)'

build.psm1

@@ -2485,14 +2485,14 @@ function Start-PSBootstrap {
             Write-LogGroupEnd -Title "Install Windows Dependencies"
         }
 
+        # Ensure dotnet is available
+        Find-Dotnet
+
         if (-not $env:TF_BUILD) {
             if ($Scenario -eq 'DotNet' -or $Scenario -eq 'Both') {
                 Write-LogGroupStart -Title "Install .NET SDK"
                 Write-Log -message "Installing .NET global tools"
 
-                # Ensure dotnet is available
-                Find-Dotnet
-
                 # Install dotnet-format
                 Write-Verbose -Verbose "Installing dotnet-format global tool"
                 Start-NativeExecution {