[build] Generate separate .binlog files for tests.

Context: dotnet#1792
Context: 944092d99540bb9a6106175404c17cf4fddce394

Commit 944092d9 updated the "normal" build log process, as used by
Jenkins/etc., so that Console output received "normal" build verbosity
messages, while MSBuild `.binlog` files would be generated so that
"diagnostic" build logs could be produced "later," as necessary.

Unfortunately, commit 944092d9 didn't update unit test builds.
Consequently, `make run-apk-tests`/etc. would emit *diagnostic* build
logs to the Console, meaning instead of the previous ~1GB log file, we
instead had a "mere" ~400MB instead.

Update test execution so that they follow the spirit of 944092d9:
`.binlog` files for diagnostic output, with "normal" output printed to
the console, resulting in smaller Jenkins log files.

build-tools/scripts/RunTests.targets

@@ -13,6 +13,7 @@
     <_XABuild>$(_TopDir)\bin\$(Configuration)\bin\xabuild</_XABuild>
     <_XABuildDiag Condition=" '$(V)' != '' ">/v:diag </_XABuildDiag>
     <_XABuildProperties>$(_XABuildDiag)/p:Configuration=$(Configuration) /p:XAIntegratedTests=$(XAIntegratedTests)</_XABuildProperties>
+    <_XABinLogPrefix>/v:normal /binaryLogger:"$(MSBuildThisFileDirectory)\..\..\bin\Build$(Configuration)\msbuild</_XABinLogPrefix>
   </PropertyGroup>
   <ItemGroup>
     <_TestAssembly Include="$(_TopDir)\bin\Test$(Configuration)\Xamarin.Android.Build.Tests.dll" />
@@ -88,13 +89,23 @@
     <Delete Files="@(_JavaInteropTestResults)" />
   </Target>
   <Target Name="RunApkTests">
-    <Exec Command="$(_XABuild) %(_ApkTestProject.Identity) /t:SignAndroidPackage $(_XABuildProperties)" />
+    <ItemGroup Condition=" '$(USE_MSBUILD)' == '1' ">
+      <_ApkTestProject>
+        <_BinLog>$(_XABinLogPrefix)-$([System.DateTime]::Now.ToString ("yyyyMMddTHHmmss"))-%(Filename).binlog"</_BinLog>
+      </_ApkTestProject>
+    </ItemGroup>
+    <Exec Command="$(_XABuild) %(_ApkTestProject.Identity) %(_ApkTestProject._BinLog) /t:SignAndroidPackage $(_XABuildProperties)" />
     <MSBuild
         ContinueOnError="ErrorAndContinue"
         Projects="$(_TopDir)\tests\RunApkTests.targets"
     />
+    <ItemGroup Condition=" '$(USE_MSBUILD)' == '1' ">
+      <_ApkTestProjectAot>
+        <_BinLog>$(_XABinLogPrefix)-$([System.DateTime]::Now.ToString ("yyyyMMddTHHmmss"))-%(Filename)-AOT.binlog"</_BinLog>
+      </_ApkTestProjectAot>
+    </ItemGroup>
     <Exec 
-        Command="$(_XABuild) %(_ApkTestProjectAot.Identity) /t:SignAndroidPackage $(_XABuildProperties) /p:AotAssemblies=True"
+        Command="$(_XABuild) %(_ApkTestProjectAot.Identity) %(_ApkTestProjectAot._BinLog) /t:SignAndroidPackage $(_XABuildProperties) /p:AotAssemblies=True"
         Condition=" '$(Configuration)' == 'Release' "
     />
     <MSBuild 
@@ -103,8 +114,13 @@
         Condition=" '$(Configuration)' == 'Release' "
         Properties="AotAssemblies=True"
     />
+    <ItemGroup Condition=" '$(USE_MSBUILD)' == '1' ">
+      <_ApkTestProjectBundle>
+        <_BinLog>$(_XABinLogPrefix)-$([System.DateTime]::Now.ToString ("yyyyMMddTHHmmss"))-%(Filename)-Bundle.binlog"</_BinLog>
+      </_ApkTestProjectBundle>
+    </ItemGroup>
     <Exec
-        Command="$(_XABuild) %(_ApkTestProjectBundle.Identity) /t:SignAndroidPackage $(_XABuildProperties) /p:BundleAssemblies=True /p:EmbedAssembliesIntoApk=True"
+        Command="$(_XABuild) %(_ApkTestProjectBundle.Identity) %(_ApkTestProjectBundle._BinLog) /t:SignAndroidPackage $(_XABuildProperties) /p:BundleAssemblies=True /p:EmbedAssembliesIntoApk=True"
         Condition=" '$(Configuration)' == 'Release' "
     />
     <MSBuild