Fix DotNetFinalVersionKind variable in yml (#170)

Use a fixed parameter list containing the 3 possible options for the DotNetFinalVersionKind global property that generates the official packages.

eng/Versions.props

@@ -3,7 +3,6 @@
   <PropertyGroup>
     <PreReleaseVersionLabel>rtm</PreReleaseVersionLabel>
     <PreReleaseVersionIteration></PreReleaseVersionIteration>
-    <DotNetFinalVersionKind>release</DotNetFinalVersionKind>
     <!-- Opt-out repo features -->
     <UseVSTestRunner>true</UseVSTestRunner>
     <UsingToolXliff>false</UsingToolXliff>

eng/pipelines/maintenance-packages.yml

@@ -1,3 +1,13 @@
+parameters:
+- name: DotNetFinalVersionKind
+  type: string
+  displayName: .NET Final Version Kind
+  values:
+  - none
+  - prerelease
+  - release
+  default: none
+
 trigger:
   batch: true
   branches:
@@ -20,11 +30,18 @@ variables:
     value: ''
   - name: _BuildJobDisplayName
     value: 'Build and Test'
+  - name: _DotNetFinalVersionKind
+    value: ''
 - ${{ else }}:
   - name: _AdditionalBuildArgs
     value: '/p:Test=false'
   - name: _BuildJobDisplayName
     value: 'Build, Sign and Publish'
+  - name: _DotNetFinalVersionKind
+    ${{ if eq(parameters.DotNetFinalVersionKind, 'none') }}:
+      value: ''
+    ${{ else }}:
+      value: /p:DotNetFinalVersionKind=${{ parameters.DotNetFinalVersionKind }}
 
 resources:
   repositories:
@@ -91,6 +108,7 @@ extends:
                 -configuration Release
                 -prepareMachine
                 /p:Test=false
+                $(_DotNetFinalVersionKind)
                 $(_AdditionalBuildArgs)
                 $(_InternalBuildArgs)
               displayName: $(_BuildJobDisplayName)