feat: Support environments with multiple languages

[terrytangyuan]

Description

Currently, we only support single language environments such as Python and R. However, some data science teams use multiple languages at the same time. For example, R users could invoke any Python libraries in R via reticulate or run R wrappers of an existing Python library such as TensorFlow for R.

We could support multiple languages in the same environment, e.g. base(language=["python", "r"]).

[gaocegege]

LGTM!

[kemingy]

Supported in v1 by https://github.com/tensorchord/envd/pull/1501