[Branding] Support for Local File Paths in branding configuration

[ABurns1263]

Is your feature request related to a problem? Please describe. My company requires being able to reference a local image for branding, instead of a url to an image, in the opensearch_dashboards.yaml file.

Describe the solution you'd like

We would like to be able to use local file paths in the branding configuration, as ssl key and configuration do in the same file.

Describe alternatives you've considered

We have tried to reference local file paths using http://localhost: http://127.0.0.1 file:/// before our local file path to icons, however these did not configure the images onto opensearch dashboards