Remove separate server hero setting

Cherry-picked d2528b26b6

Conflicts:
- `app/serializers/initial_state_serializer.rb`:
  Upstream changed stuff, we had extra attributes.
  Applied upstream changes while keeping our extra attributes.
- `app/serializers/rest/instance_serializer.rb`:
  Upstream actually moved that to `app/serializers/rest/v1/instance_serializer.rb`,
  so updated that file by keeping our extra attributes, and took upstream's
  version of `app/serializers/rest/instance_serializer.rb`.
- `spec/views/about/show.html.haml_spec.rb`:
  Took upstream's version.

* Remove duplicate in_chosen_languages definition

* Use `DEFAULT_FIELDS_SIZE` instead of `MAX_FIELDS` to reduce code differences with upstream

* Remove duplicate annotation

* Fix incorrect cross-flavor imports

* Remove deprecated `hide_network` setting (replaced by account column)

* Remove unused KeywordMutesHelper

* Remove trailing spaces

* Remove commit_hash from InstancePresenter, as it has been unused since mid-2017

- Reduce duplicate queries
- Remove n+1 queries
- Add accounts count to detailed view
- Add separate action log entry for updating existing domain blocks

Fix #12003

* Add nodeinfo endpoint

* dont commit stuff from my local dev

* consistant naming since we implimented 2.1 schema

* Add some additional node info stuff

* Add nodeinfo endpoint

* dont commit stuff from my local dev

* consistant naming since we implimented 2.1 schema

* expanding this to include federation info

* codeclimate feedback

* CC feedback

* using activeserializers seems like a good idea...

* get rid of draft 2.1 version

* Reimplement 2.1, also fix metaData -> metadata

* Fix metaData -> metadata here too

* Fix nodeinfo 2.1 tests

* Implement cache for monthly user aggregate

* Useless

* Remove ostatus from the list of supported protocols

* Fix nodeinfo's open_registration reading obsolete setting variable

* Only serialize domain blocks with user-facing limitations

* Do not needlessly list noop severity in nodeinfo

* Only serialize domain blocks info in nodeinfo when they are set to be displayed to everyone

* Enable caching for nodeinfo endpoints

* Fix rendering nodeinfo

* CodeClimate fixes

* Please CodeClimate

* Change InstancePresenter#active_user_count_months for clarity

* Refactor NodeInfoSerializer#metadata

* Remove nodeinfo 2.1 support as the schema doesn't exist

* Clean-up

* Fix admin validation being too strict about usernames

Fix #10446

* Strip Setting.site_contact_username consistently throughout the codebase

Fix #6856
Fix #6951

Fix #7637

It is returned as a double because the sum is now over bigint columns

Fix #9312

Fix #3894

* Add separate setting for sidebar text (site_short_description)

* Fix tests

* Redesign landing page (again)

* Move login form in small version to the right column

* Display closed registrations message

* Add site setting for the hero image

* Fix test

* Increase spacing, maximum width, change call to action section

It is faster.

* Improve OpenGraph tags for about pages

* Add thumbnail admin setting

* Fix error

* Fix up

* Add Mastodon::Source.url

* Update spec

* Refactor

Move things frmo Mastodon::Source to Mastodon::Version

* First lame pass at adding optional git commit hash display on /about/more page.

Currently, this is implemented by checking for the existence of a file called CURRENT_RELEASE in the home directory of the user running Mastodon. If the file exists, its contents are added.

I've modified my update process to include the following before precompiling assets:

git log -1 | head -n 1 | cut -d " " -f2 > ~/CURRENT_RELEASE

That puts the current commit hash into the file ~/CURRENT_RELEASE, but you figured that out because you're a smart cookie.

As I am quite sure this is a horrible methodology for implementing this, I look forward to any improvements you have to offer!

* Updated to handle instances that share a user - the CURRENT_RELEASE file now lives in the instance's base directory.

This also requires modifying the update hook to `git log -1 | head -n 1 | cut -d " " -f2 > CURRENT_RELEASE`

* Redesign the landing page, mount public timeline on it

* Adjust the standalone mounted component to the lacking of router

* Adjust auth layout pages to new design

* Fix tests

* Standalone public timeline polling every 5 seconds

* Remove now obsolete translations

* Add responsive design for new landing page

* Address reviews

* Add floating clouds behind frontpage form

* Use access token from public page when available

* Fix mentions and hashtags links, cursor on status content in standalone mode

* Add footer link to source code

* Fix errors on pages that don't embed the component, use classnames

* Fix tests

* Change anonymous autoPlayGif default to false

* When gif autoplay is disabled, hover to play

* Add option to hide the timeline preview

* Slightly improve alt layout

* Add elephant friend to new frontpage

* Display "back to mastodon" in place of "login" when logged in on frontpage

* Change polling time to 3s

* Adds version.

* Cleans up code.

* Removes standalone endpoint and adds version to instance endpoint.

* Addresses feedback from #2181.

* Correct site_contact_email typo

* Separate about more page into partials, add specs

* Add InstancePresenter to expose site details

* Clean up about controller, use instance presenter