Let Expo/Webpack handle CSS assets

[mary-ext]

Stacked on #3929, see #3929 (comment)

Manually sharing CSS code between web/index.html (dev builds) and bskyweb/templates/base.html (production) is brittle, let's have it handled as a built asset instead.

This also means hot-reloading on development, well, hopefully it should.

Small savings gained from minification (reduction of ~2kb uncompressed)

[mary-ext]

Never even noticed the double closing tag until now 😅

[mary-ext]

This import order isn't right, ideally this should be imported very last but the ESLint sort import plugin doesn't seem to like that, not sure what I'd do to make this right. Maybe it's okay right now though.

[mozzius]

you can edit the sort plugin's order to put css files at the end

[mary-ext]

Yeah, that's what I was unsure about, because according to the config it should be putting relative imports last?

social-app/.eslintrc.js

Lines 52 to 64 in 195c9f1

	// Relative imports.
	// Ideally, anything that starts with a dot or #
	// due to unprefixed relative imports being used, we whitelist the relative paths we use
	// (?:$|\\/) matches end of string or /
	[
	'^(?:#\\/)?(?:lib|state|logger|platform|locale)(?:$|\\/)',
	'^(?:#\\/)?view(?:$|\\/)',
	'^(?:#\\/)?screens(?:$|\\/)',
	'^(?:#\\/)?alf(?:$|\\/)',
	'^(?:#\\/)?components(?:$|\\/)',
	'^#\\/',
	'^\\.',
	],