Fix/import path colang 2

[Pouyanpi]

Description

If you import nemoguardrails standard library in a Colang 2.x config _load_imported_path function fails.

WAR: export path to root of nemoguardrails as "COLANGPATH" env var.

Limitation: the standard library must be included by default, also if the user install the wheel it does not work because it needs to be set to its location in a virtual environment

Steps to reproduce:

cd ./examples/bots/abc_v2
nemoguardrails chat --config=.

Related Issue(s)

Checklist

• [x] I've read the CONTRIBUTING guidelines.
• [x] I've updated the documentation if applicable.
• [x] I've added tests if applicable.
• [x] @mentions of the person or team responsible for reviewing proposed changes.