Add ARM dev environment dependencies

[dgerlanc]

The environment-arm.yml file is a copy of environment.yml with Intel MKL dependencies replaced with OpenBLAS.

We may want to update the documentation on installing aesara on Mac OS or complete the fix for #127 before merging this PR. Without resolving #127, aesara will continue to have problems on Mac OS.

I have started a branch re: #127 here.

Currently, with this environment, you can create a working OS X environment for aesara so long as you update the cxxflags, e.g. setting ~/.aesararc to:

[global]

[gcc]
cxxflags=-Wno-c++11-narrowing

Resolves: #934

[twiecki]

I think in general, fixing the blas implementation is a bit heavy-handed. Ideally there are instructions on which to use, even though it's a bit confusing for users.

What are these env files actually used for? We have better ones in the conda-forge repo where mkl was already removed.

[dgerlanc]

I think in general, fixing the blas implementation is a bit heavy-handed. Ideally there are instructions on which to use, even though it's a bit confusing for users. What are these env files actually used for? We have better ones in the conda-forge repo where mkl was already removed.

The environment.yml and environment-arm.yml can be used to create a dev environment on x86 or Arm. In theory, users should not be getting involved with these and just including aesara and their desired BLAS implementation in their project environment.yml.

We should indicate in the documentation that these are to be used if you want to contribute to aesara, not simply use it as a library.