Removing fetching action function name from action_functions dictionary.

[petar-qb]

Description

Now, users are able to create their own custom actions in a following way:

# Defining custom action function
from vizro.models.types import capture

@capture("action")
def custom_action(**inputs):
    print("custom action triggered")
    print(inputs)
    return inputs

# Action model example
vm.Action(
    function=custom_action(),
    inputs=['button_id.value'],
    outputs=['button_id.value'],
)

Screenshot

Checklist

• I have not referenced individuals, products or companies in any commits, directly or indirectly
• I have not added data or restricted code in any commits, directly or indirectly
• I have updated the docstring of any public function/class/model changed
• I have added the PR number to the change description in the changelog fragment, e.g. Enable feature XXX ([#1](https://github.com/mckinsey/vizro/pull/1)) (if applicable)

Types of changes

• Docs/refactoring (non-breaking change which improves codebase)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[maxschulz-COL]

lgtm! Thanks

[nadijagraca]

Looks good.