Add conda CI

[jfdev001]

Another thing that would be nice, I guess, would be to add some conda CI.
Though I accept this is a bigger task and would require a separate PR

Originally posted by @jatkinson1000 in #430

[jwallwork23]

Could possibly use the matrix concept to support different build approaches within a single workflow definition, along with spack and fpm (to be added in #271, #429).

[jfdev001]

Per #430 (comment) during CMAKE_BUILD_TESTS, a check should be added for the CONDA_PREFIX since currently there is a check for VIRTUAL_ENV (which could be set as something like export VIRTUAL_ENV=$(pwd)/.venv/bin if using venv) as in

FTorch/CMakeLists.txt

Line 169 in f230be8

if(NOT DEFINED ENV{VIRTUAL_ENV})

but we should also catch conda envs too by changing it to

if(NOT DEFINED ENV{VIRTUAL_ENV} AND NOT DEFINED ENV{CONDA_PREFIX})

This change really only becomes relevant once conda is included in the CI, though.