Add a dev-envrionment.yml to simplify setting up a dev environment

[ngoldbaum]

This defines a conda environment suitable for bootstrapping csp development. If we add this and update the build instructions in the wiki to use it, we can get rid of a big chunk of the OS-specific build environment setup instructions.

I successfully built csp and ran the tests on a M3 Macbook Pro and a aarch64 Ubuntu VM running on the same machine and this seems to work on both systems.

To get this to work, you'll need to install anaconda or miniconda, such that conda is visible in your PATH, with the following configuation settings to activate conda-forge:

$ conda config --add channels conda-forge
$ conda config --set channel_priority strict

Then create a new conda environment using this file and activate it:

$ conda env create -n csp -f dev-environment.yml
$ conda activate csp

And then build and install csp into conda's python environment as discussed in the wiki.

Note that users on macs will still need to get gcc from homebrew and manually specify homebrew's g++ in their make build command since conda-forge doesn't provide g++ except on linux.

If this is OK as-is and it can be merged, I'll update the build instructions on the wiki to suggest starting with a conda environment and to use this file. I'll go ahead and leave the OS-specific non-conda instructions as well, but move them to a less prominent place.

[timkpaine]

lgtm, the g++ dependency hopefully won't exist for a very long time. I would just put conda as an option before Linux on the developer docs as many people (myself included) don't use conda, and there are some major pitfalls of trying to use a conda environment for publishing pypa wheels.

[timkpaine]

@ngoldbaum please edit as needed https://github.com/Point72/csp/wiki/99.-Developer#conda