Implement new designs for in-call footer buttons

This basically amounts to swapping out some CSS, the icons, and the Tooltip component.

public/locales/en-GB/app.json

@@ -40,6 +40,7 @@
   "Element Call Home": "Element Call Home",
   "Element Call is temporarily not end-to-end encrypted while we test scalability.": "Element Call is temporarily not end-to-end encrypted while we test scalability.",
   "Enable end-to-end encryption (password protected calls)": "Enable end-to-end encryption (password protected calls)",
+  "End call": "End call",
   "End-to-end encryption isn't supported on your browser.": "End-to-end encryption isn't supported on your browser.",
   "Exit full screen": "Exit full screen",
   "Expose developer settings in the settings window.": "Expose developer settings in the settings window.",
@@ -61,15 +62,15 @@
   "Join call": "Join call",
   "Join call now": "Join call now",
   "Join existing call?": "Join existing call?",
-  "Leave": "Leave",
   "Loading…": "Loading…",
   "Local volume": "Local volume",
   "Logging in…": "Logging in…",
   "Login": "Login",
   "Login to your account": "Login to your account",
   "Microphone": "Microphone",
+  "Microphone off": "Microphone off",
+  "Microphone on": "Microphone on",
   "More": "More",
-  "Mute microphone": "Mute microphone",
   "No": "No",
   "Not now, return to home screen": "Not now, return to home screen",
   "Not registered yet? <2>Create an account</2>": "Not registered yet? <2>Create an account</2>",
@@ -91,13 +92,13 @@
   "Sending…": "Sending…",
   "Settings": "Settings",
   "Share screen": "Share screen",
+  "Sharing screen": "Sharing screen",
   "Show call inspector": "Show call inspector",
   "Show connection stats": "Show connection stats",
   "Sign in": "Sign in",
   "Sign out": "Sign out",
   "Speaker": "Speaker",
   "Spotlight": "Spotlight",
-  "Stop sharing screen": "Stop sharing screen",
   "Submit": "Submit",
   "Submit feedback": "Submit feedback",
   "Submitting…": "Submitting…",
@@ -107,15 +108,14 @@
   "This call already exists, would you like to join?": "This call already exists, would you like to join?",
   "This call is not end-to-end encrypted.": "This call is not end-to-end encrypted.",
   "This site is protected by ReCAPTCHA and the Google <2>Privacy Policy</2> and <6>Terms of Service</6> apply.<9></9>By clicking \"Register\", you agree to our <12>End User Licensing Agreement (EULA)</12>": "This site is protected by ReCAPTCHA and the Google <2>Privacy Policy</2> and <6>Terms of Service</6> apply.<9></9>By clicking \"Register\", you agree to our <12>End User Licensing Agreement (EULA)</12>",
-  "Turn off camera": "Turn off camera",
-  "Turn on camera": "Turn on camera",
-  "Unmute microphone": "Unmute microphone",
   "User menu": "User menu",
   "Username": "Username",
   "Version: {{version}}": "Version: {{version}}",
   "Video": "Video",
   "Video call": "Video call",
   "Video call name": "Video call name",
+  "Video off": "Video off",
+  "Video on": "Video on",
   "Waiting for other participants…": "Waiting for other participants…",
   "Walkie-talkie call": "Walkie-talkie call",
   "Walkie-talkie call name": "Walkie-talkie call name",