MAINT: cleaner handling of latest conda and dev conda

[ZLLentz]

Description

• For dev_conda, use the latest tag as a base instead of an arbitrary outdated dev environment. This gives us a better chance of dev always being up-to-date and stable.
• For pcds_conda and dev_conda, find the latest tag via config file instead of automatically.

Motivation and Context

The outdated dev environment is causing issues because the base packages are so far behind and it's not possible to update it safely in-place. The dynamically picked pcds_conda environment path causes issues (closes #136) Now, we will be able to test and vet the fully installed environment before dropping people into it by default.

I've placed the config file for this inside of the conda environment itself. This keeps it one level hidden from accidental changes and allows a different config seamlessly when we boost to the next version of Python.

See /cds/group/pcds/pyps/conda/py39/latest_env

How Has This Been Tested?

Interactively only.

Where Has This Been Documented?

N/A, should be transparent to users.

[ZLLentz]

This is not to be deployed prior to the pamm in case the updated dev causes unforeseen and esoteric issues.

[ZLLentz]

Great! I'll merge and send out an additional engineering_tools tag during the POMM a week from today.