conference: add raise hand

Ring/Ring/Bridging/CallsAdapter.h

Ring/Ring/Bridging/CallsAdapter.mm

Ring/Ring/Calls/ButtonsContainerView.swift

Ring/Ring/Calls/ButtonsContainerView.xib

Ring/Ring/Calls/CallViewController.swift

Ring/Ring/Calls/CallViewModel.swift

Ring/Ring/Calls/Conference/ConferenceLayout.swift

Ring/Ring/Calls/Conference/ConferenceMenuItemsManager.swift

Ring/Ring/Calls/views/ConferenceActionsMenu.swift

Ring/Ring/Constants/Generated/Images.swift

Ring/Ring/Constants/Generated/Strings.swift

Ring/Ring/Extensions/UIColor+Ring.swift

Ring/Ring/Models/ConferenceParticipant.swift

...sources/Images.xcassets/raise_hand.imageset/Contents.json

...ources/Images.xcassets/raise_hand.imageset/hand_black.png

...ces/Images.xcassets/raise_hand.imageset/hand_black_50.png

...ces/Images.xcassets/raise_hand.imageset/hand_black_75.png

Ring/Ring/Resources/en.lproj/Localizable.strings

Ring/Ring/Services/CallsService.swift