Recycling POI block

[bbecquet]

Description

Implement a "Recycling" POI block, to display details about recycling containers.

Note
This PR is quite big for such content as I used it as an excuse to introduce things that I think were currently missing and can ease development for all parts of the app in the future:

• I introduced a generic <Flex> component. It's very basic for now, to be completed when needed and/or replaced by a similar component from the Qwant Design System if we find a way to use it one day… The goal is to promote the use of the flex layout in a standard way, instead of floats or absolute positionings that are still used in many parts of the app with a lot of unnecessary CSS and many inconsistencies.
• I introduced a generic <Text> component, to standardize the typographic classes beyond just CSS and do common patterns in a consistent way (like displaying an icon before the text). As for <Flex>, it's meant to be re-used anywhere possible, adapted to our needs and replaced by a Design System component when the time is right.
• I developed the <Meter> component as a shared one, so it can be re-used easily in other parts if needed. BTW, it's a choice not to use the native meter HTML element, as it's a real hell to style properly and would introduce broken designs on older browsers.
• I introduced a way to export individual generic components from a centralized file, so they can be imported more easily. Once again, the idea is to encourage their use. So, instead of:

import Flex from 'src/components/ui/Flex';
import Text from 'src/components/ui/Text';
import Meter from 'src/components/ui/Meter';

It's now possible to do:

import { Flex, Text, Meter } from 'src/components/ui';

Screenshots