Add ability to isolate paths for roles and collection

[tierpod]

Hello. Molecule set ANSIBLE_COLLECTIONS_PATH and ANSIBLE_ROLES_PATH vars quite wide - it adds user's home and system-wide directories:

ANSIBLE_COLLECTIONS_PATH="...~/.ansible/collections:/usr/share/ansible/collections:/etc/ansible/collections"
ANSIBLE_ROLES_PATH="...~/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:/path/to/roles_path"

It can lead to tricky situation. I think it would be useful to have ability to completely isolate these paths to self._config.scenario.config.runtime.cache_dir or self._config.scenario.ephemeral_directory (provisioner/ansible.py).

Use case: I have a role tested with molecule. After some changes, this role now call ansible.posix.authorized_keys from ansible.posix collection. On my machine it works, but on CI/CD it fails. After some investigation I found out, that I have this collection installed to my home directory (~/.ansible/collections), because some other local playbooks uses it, and molecule uses this collection from there.

I know, it's my fault - I should have added this collection to requirements.yml. But I think, it would be better if molecule have failed in such cases with error like "cannon find ansible.posix collection" instead of using global-installed collection.

[tierpod]

I played with molecule and it looks like this patch does what I want:

--- ansible.py_orig	2023-02-07 14:23:55.353889956 +0500
+++ ansible.py	2023-02-07 14:20:48.539619778 +0500
@@ -455,15 +455,6 @@
                 collection_indicator, 1
             )
             collections_path_list.append(util.abs_path(collection_path))
-        collections_path_list.extend(
-            [
-                util.abs_path(
-                    os.path.join(os.path.expanduser("~"), ".ansible/collections")
-                ),
-                "/usr/share/ansible/collections",
-                "/etc/ansible/collections",
-            ]
-        )
 
         if os.environ.get("ANSIBLE_COLLECTIONS_PATH", ""):
             collections_path_list.extend(
@@ -482,9 +473,6 @@
                 os.path.join(self._config.scenario.ephemeral_directory, "roles")
             ),
             util.abs_path(os.path.join(self._config.project_directory, os.path.pardir)),
-            util.abs_path(os.path.join(os.path.expanduser("~"), ".ansible", "roles")),
-            "/usr/share/ansible/roles",
-            "/etc/ansible/roles",
         ]
 
         if os.environ.get("ANSIBLE_ROLES_PATH", ""):