Make filepicker readDirMsg public

[mJehanno]

Is your feature request related to a problem? Please describe.
I'm using the filepicker bubble inside a bubbleboxer model but even though the init command of the filepicker is well propagated, the readDirMsg doesn't get to the filepicker. I'm probably doing something wrong on my side but I think it would just be easier to be able to filter on that particular message in a switch case block.

Describe the solution you'd like
I think it could be great to make the readDirMsg public. Many bubbles have their main message exposed, but not the filepicker

Describe alternatives you've considered
Didn't find any yet

Additional context
My code looks like this :

func (f FilePickerHolderModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
    var cmd tea.Cmd
    log.Info(msg) // my array of file
    log.Infof("msg type : %T", msg) // readDirMsg
    f.fp, cmd = f.fp.Update(msg)
    return f,cmd
}