Add the variable OPS_DIR and OPS_FILE in ops

[sciabarracom]

Why you need it?

We need a variable OPS_DIR pointing to the directory where the current opsfile resides.
This is because if you change for example to $OPS_PWD you may beed to refer to the original folder of the opsfile, for example to run

uv --directory $OPS_DIR run python main.py

How it could be?

Add the OPS_DIR of the taskfile you found to the environment and document it
Also OPS_FILE to point to the current opsfile.yml is useful