app/javascript/mastodon/main.js delayed the execution of modules,
but other entry points didn't. That leads to failure in executing
modules, which requires those polyfills.

Strictly enforce the rule to require any modules after loading
polyfill in entry points.

* feat: Register push subscription

* feat: Notify when mentioned

* feat: Boost, favourite, reply, follow, follow request

* feat: Notification interaction

* feat: Handle change of public key

* feat: Unsubscribe if things go wrong

* feat: Do not send normal notifications if push is enabled

* feat: Focus client if open

* refactor: Move push logic to WebPushSubscription

* feat: Better title and body

* feat: Localize messages

* chore: Fix lint errors

* feat: Settings

* refactor: Lazy load

* fix: Check if push settings exist

* feat: Device-based preferences

* refactor: Simplify logic

* refactor: Pull request feedback

* refactor: Pull request feedback

* refactor: Create /api/web/push_subscriptions endpoint

* feat: Spec PushSubscriptionController

* refactor: WebPushSubscription => Web::PushSubscription

* feat: Spec Web::PushSubscription

* feat: Display first media attachment

* feat: Support direction

* fix: Stuff broken while rebasing

* refactor: Integration with session activations

* refactor: Cleanup

* refactor: Simplify implementation

* feat: Set VAPID keys via environment

* chore: Comments

* fix: Crash when no alerts

* fix: Set VAPID keys in testing environment

* fix: Follow link

* feat: Notification actions

* fix: Delete previous subscription

* chore: Temporary logs

* refactor: Move migration to a later date

* fix: Fetch the correct session activation and misc bugs

* refactor: Move migration to a later date

* fix: Remove follow request (no notifications)

* feat: Send administrator contact to push service

* feat: Set time-to-live

* fix: Do not show sensitive images

* fix: Reducer crash in error handling

* feat: Add badge

* chore: Fix lint error

* fix: Checkbox label overlap

* fix: Check for payload support

* fix: Rename action "type" (crash in latest Chrome)

* feat: Action to expand notification

* fix: Lint errors

* fix: Unescape notification body

* fix: Do not allow boosting if the status is hidden

* feat: Add VAPID keys to the production sample environment

* fix: Strip HTML tags from status

* refactor: Better error messages

* refactor: Handle browser not implementing the VAPID protocol (Samsung Internet)

* fix: Error when target_status is nil

* fix: Handle lack of image

* fix: Delete reference to invalid subscriptions

* feat: Better error handling

* fix: Unescape HTML characters after tags are striped

* refactor: Simpify code

* fix: Modify to work with #4091

* Sort strings alphabetically

* i18n: Updated Polish translation

it annoys me that it's not fully localized :P

* refactor: Use current_session in PushSubscriptionController

* fix: Rebase mistake

* fix: Set cacheName to mastodon

* refactor: Pull request feedback

* refactor: Remove logging statements

* chore(yarn): Fix conflicts with master

* chore(yarn): Copy latest from master

* chore(yarn): Readd offline-plugin

* refactor: Use save! and update!

* refactor: Send notifications async

* fix: Allow retry when push fails

* fix: Save track for failed pushes

* fix: Minify sw.js

* fix: Remove account_id from fabricator

Require stylesheets in common.js because stylesheets are shared by the
entry points.

This implementation is a bit smaller and still has the following benefits:

* No need of app/javascript/packs/custom.js
For custom stylesheet, it typically has only
"require('../styles/custom.scss')" and is redundant.

* No need to extract vendor stylesheet to another asset
Extracting vendor stylesheet could be forgotten by developers who do not
use custom stylesheet.

* Fix #2922 - Load stylesheet from "custom.css" entrypoint when present

This is pretty much the same way it worked as before, albeit with
having to create app/javascript/packs/custom.js with
require('../styles/custom.scss') (or whatever you want really), which
will be a blank slate for you to import whatever you want

* Remove old assets directory

* Extract font-awesome into common.css and always load it

* Add semi to ESLint rules

* Add padded-blocks to ESLint rules

* Add comma-dangle to ESLint rules

* add config/webpack and storyboard

* add streaming/

* yarn test:lint -- --fix

* Create common chunk rather than vendor chunk

vendor chunk is a set of modules provided by external vendors, but now we
can have a chunk as a set of modules shared by multiple entry points,
which could be more efficent than having vendor chunk.

* Start rails-ujs in common.js

This is used by /settings/two_factor_authentication.

* Allow SCSS variables to be overridden with
  `app/javascript/pack/variables*.scss`

* Allow these SCSS variables to be overriden:
  * `$base-shadow-color`
  * `$base-overlay-background`
  * `$base-border-color`
  * `$simple-background-color`
  * `$primary-text-color`
  * `$valid-value-color
  * `$error-value-color`

Fixes #2941