Add tooltip feature for buttons without label

...uebutton-html5/imports/ui/components/button/component.jsx

...l5/imports/ui/components/chat/chat-dropdown/component.jsx

bigbluebutton-html5/imports/ui/components/chat/component.jsx

bigbluebutton-html5/imports/ui/components/chat/styles.scss

...ebutton-html5/imports/ui/components/tooltip/component.jsx

bigbluebutton-html5/package-lock.json

bigbluebutton-html5/package.json