Local extra-dep executable overwritten by project package executable, without warning

It appears that:
* built executables of a local extra-dep are installed in the `install\\bin` directory of the project's Stack work directory; and
* built executables of a project package are installed in the same directory.

In the case of project packages with executables with the same name, Stack issues a warning. That is handled by `Stack.Build.warnIfExecutablesWithSameNameCouldBeOverwritten` (following resolution of #1198). However, no warning is triggered if the clash involves a local extra-dep's executable.

~~~
stack --version
Version 2.16.0, Git revision 2adc11c27bdaa6a49b1cfeeebb1299710f865185 (dirty) (10623 commits) PRE-RELEASE x86_64
~~~