feat: Component placement data can now be imported/exported to files …

[devbisme]

…selected by a file browser dialog.

A file browser is now used to select the file with the YAML component placement info instead of using the fixed layout.yaml file. You can also export the component placement info to selected YAML file.

I understand if you don't want to accept a PR with so many changes. If so, I'll just make an inpedendent repo and reference your contributions.