EXP-1476 FIXED (Moving speak button to empty toolbar while incoming/outgoing...

EXP-1476 FIXED (Moving speak button to empty toolbar while incoming/outgoing call dialog is open does not move the dialog as well)
Reason:
A floater can be docked only to a button which is in visible chain, the visibility of the button itself is not enough.
After the button was added to the empty toolbar: mButtonAddSignal is called and the floater tries to dock to the button, but the button's parent(mButtonPanel) is yet invisible at this moment (so the button is not in visible chain). mButtonPanel visibility updates in draw() depending on whether it contains some buttons or not.

Solution:
Updating mButtonPanel visibility right after the button was added, before mButtonAddSignal