Add end-to-end cabal-install test for "build-tool-depends"

cabal-install/cabal-install.cabal

...ll/tests/IntegrationTests/new-build/build_tool_depends.sh

...tegrationTests/new-build/build_tool_depends/cabal.project

...grationTests/new-build/build_tool_depends/client/Hello.hs

...ionTests/new-build/build_tool_depends/client/client.cabal

...build/build_tool_depends/pre-proc/MyCustomPreprocessor.hs

...ests/new-build/build_tool_depends/pre-proc/pre-proc.cabal