Restore use of $(IntermediateOutputPath) in ApiCompat commands (#5373)

- #5361
- pass property value in `--impl-dirs` argument in `ValidateApiCompatForSrc` target
- reverts small part of #4585
  - specifically, restore one line changed in 24d6981

src/Microsoft.DotNet.ApiCompat/build/Microsoft.DotNet.ApiCompat.targets

@@ -68,7 +68,7 @@
       <ApiCompatArgs Condition="'$(ApiCompatExcludeAttributeList)' != ''">$(ApiCompatArgs) --exclude-attributes "$(ApiCompatExcludeAttributeList)"</ApiCompatArgs>
       <ApiCompatArgs Condition="'$(ApiCompatEnforceOptionalRules)' == 'true'">$(ApiCompatArgs) --enforce-optional-rules</ApiCompatArgs>
       <ApiCompatArgs Condition="'$(BaselineAllAPICompatError)' != 'true' and Exists('$(ApiCompatBaseline)')">$(ApiCompatArgs) --baseline "$(ApiCompatBaseline)"</ApiCompatArgs>
-      <ApiCompatArgs>$(ApiCompatArgs) --impl-dirs "@(_DependencyDirectories, ','),"</ApiCompatArgs>
+      <ApiCompatArgs>$(ApiCompatArgs) --impl-dirs "$(IntermediateOutputPath),@(_DependencyDirectories, ','),"</ApiCompatArgs>
       <ApiCompatArgs Condition=" '$(AdditionalApiCompatOptions)' != '' ">$(ApiCompatArgs) $(AdditionalApiCompatOptions)</ApiCompatArgs>
       <ApiCompatBaselineAll Condition="'$(BaselineAllAPICompatError)' == 'true'">&gt; "$(ApiCompatBaseline)"</ApiCompatBaselineAll>
       <ApiCompatExitCode>0</ApiCompatExitCode>