Bump main branding to 8.0 (#73985)

* eng/Versions.props

* Directory.Build.props

* src/libraries/Microsoft.VisualBasic.Core/Directory.Build.props

* Apply suggestions from code review
Co-authored-by: NViktor Hofer <viktor.hofer@microsoft.com>
Co-authored-by: Ncarlossanlop <carlossanlop@users.noreply.github.com>
Co-authored-by: NViktor Hofer <viktor.hofer@microsoft.com>

eng/Versions.props

 <Project>
   <PropertyGroup>
     <!-- The .NET product branding version -->
-    <ProductVersion>7.0.0</ProductVersion>
+    <ProductVersion>8.0.0</ProductVersion>
     <!-- File version numbers -->
-    <MajorVersion>7</MajorVersion>
+    <MajorVersion>8</MajorVersion>
     <MinorVersion>0</MinorVersion>
     <PatchVersion>0</PatchVersion>
     <SdkBandVersion>7.0.100</SdkBandVersion>
-    <PreReleaseVersionLabel>rc</PreReleaseVersionLabel>
+    <PreReleaseVersionLabel>alpha</PreReleaseVersionLabel>
     <PreReleaseVersionIteration>1</PreReleaseVersionIteration>
     <!-- Set assembly version to align with major and minor version,
          as for the patches and revisions should be manually updated per assembly if it is serviced. -->
-    <AssemblyVersion>$(MajorVersion).$(MinorVersion).0.0</AssemblyVersion>
+    <AssemblyVersion>7.$(MinorVersion).0.0</AssemblyVersion>
     <!-- Enable to remove prerelease label. -->
     <StabilizePackageVersion Condition="'$(StabilizePackageVersion)' == ''">false</StabilizePackageVersion>
     <DotNetFinalVersionKind Condition="'$(StabilizePackageVersion)' == 'true'">release</DotNetFinalVersionKind>

src/libraries/Microsoft.VisualBasic.Core/Directory.Build.props

@@ -4,7 +4,8 @@
     <!-- We need to set MajorVersion so that FileVersion is set correctly and is
     greater than the one in the previous release -->
     <MajorVersion>$([MSBuild]::Add($(MajorVersion), 5))</MajorVersion>
-    <AssemblyVersion>$(MajorVersion).$(MinorVersion).0.0</AssemblyVersion>
+    <!-- TODO: Change back to $(MajorVersion) when assembly versions are updated. -->
+    <AssemblyVersion>12.$(MinorVersion).0.0</AssemblyVersion>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
   </PropertyGroup>