feat(conda): share envs with transformer-based backends (#1465)

* feat(conda): share env between diffusers and bark

* Detect if env already exists

* share diffusers and petals

* tests: add petals

* Use smaller model for tests with petals

* test only model load on petals

* tests(petals): run only load model tests

* Revert "test only model load on petals"

This reverts commit 111cfa97f1.

* move transformers and sentencetransformers to common env

* Share also transformers-musicgen

backend/python/petals/test.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+##
+## A bash script wrapper that runs the transformers server with conda
+
+# Activate conda environment
+source activate transformers
+
+# get the directory where the bash script is located
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+
+python -m unittest $DIR/test_petals.py