Convert entry_points to dotted notation

[MHendricks]

Convert the entry point's _ separator to . to be inline with the group spec of https://packaging.python.org/en/latest/specifications/entry-points/#data-model. The hab-gui pull request is part of this change.

I don't like making this kind of re-factor of a released feature but I think we should be using the same naming convention for entry_point groups in case we ever wanted to use the same group names for traditional entry_points.

Checklist

• I have read the CONTRIBUTING.md document
• I formatted my changes with black
• I linted my changes with flake8
• I have added documentation regarding my changes where necessary
• Any pre-existing tests continue to pass
• Additional tests were made covering my changes

Types of Changes

• Bugfix (change that fixes an issue)
• New Feature (change that adds functionality)
• Documentation Update (if none of the other choices apply)

Proposed Changes

[MHendricks]

If you are using the existing entry_point group names you can support migration by adding the old and new groups. Once you update all hosts to the new hab version you can drop the old names.

[MHendricks]

This affects the following entry_points:

• cli -> hab.cli
• launch_cls - > hab.launch_cls

Example for migrating a site json file.

{
    "append": {
        "entry_points": {
 +            "hab.cli": {
+                 "gui": "hab_gui.cli:gui"
+             },
+             // TODO: Once hab>=0.29.0 is fully released, we can drop the "cli" duplicate
            "cli": {
                "gui": "hab_gui.cli:gui"
            }
        }
    }
}

Example for migrating a launch_cls call on an alias in a .hab.json file.

{
    "name": "houdini19.5",
    "aliases": {
        "windows": [
            [
                "houdinicore", {
                    "cmd": "C:\\Program Files\\Side Effects Software\\Houdini 19.5.716\\bin\\houdinicore.exe",
+                     // when launching houdini's gui. Just use the standard class
+                     "hab.launch_cls": {"subprocess": "subprocess:Popen"},
+                     // TODO: Remove "launch_cls" keys once hab>=0.29.0 is released everywhere
                    "launch_cls": {"subprocess": "subprocess:Popen"}
                }
            ]
        ]
    }
}

Once hab has been updated on all hosts, you can safely remove the legacy entry_points without the package prefix.