Update the bg color of the invite buttons and missedNotif badge

[giomfo]

Currently we lost the background color of the missedNotifAndUnreadBadgeBgView, used for pending invite and unread messages badge when there is at least one missed highlighted notif:

in Tchapv1 this color in the dark blue Tchap:

(We will have to ckeck later with the designers, this color and if they don't want a red one for missed notifications)

[giomfo]

Define a text color to display a text on an object with the tintcolor as background color

Create an issue in Element-ios to handle this request

[giomfo]

Update:
@phlniji FYI the request here is to have the same color set as Element by considering the right tint color (Tchap blue instead of Element green)
now

Note: FYI we will have to switch back the room cell to the Element one (#468). Let me know if you prefer to do this change at the same time