Fix leaking private configuration parameters in Mastodon and Twitter APIs, and add new configuration parameters to Mastodon API

This patch:
- Fixes `rights` in TwitterAPI ignoring `show_role` 
- Fixes exposing default scope of the user to anyone in Mastodon API
- Extends Mastodon API to be able to show and set `no_rich_text`, `default_scope`, `hide_follows`, `hide_followers`, `hide_favorites` (requested by the FE in #674)

Sorry in advance for 500 line one commit diff, I should have split it up to separate MRs

See merge request pleroma/pleroma!1093

update Changelog

See merge request pleroma/pleroma!1096

Add mediaproxy whitelist capability

Closes #837

See merge request pleroma/pleroma!1095

activitypub: transmogrifier: send reject follow if following does not succeed

See merge request pleroma/pleroma!1094

Fix leaking private configuration parameters in Mastodon and Twitter APIs, and add new configuration parameters to Mastodon API

This patch:
- Fixes `rights` in twitterapi ignoring `show_role`
- Fixes exposing default scope of the user to anyone in Mastodon API
- Extends Mastodon API to be able to show and set `no_rich_text`, `default_scope`, `hide_follows`, `hide_followers`, `hide_favorites` (requested by the FE in #674)

Sorry in advance for 500 line one commit diff, I should have split it up to separate MRs

html: lock down allowed class attributes to only those related to microformats

See merge request pleroma/pleroma!1090

Extend Mastodon API with public endpoint for getting Favorites timeline of any user (#789)

Closes #789

See merge request pleroma/pleroma!1056

Add `in_reply_to_account_acct` to MastoAPI status entity

See merge request pleroma/pleroma!1086

Normalize acitvities instead of objects inside them

See merge request pleroma/pleroma!1085

Add shortcode_globs setting to documentation

See merge request pleroma/pleroma!1087

added healthcheck setting to instance config

See merge request pleroma/pleroma!1088

Replace Object.normalize(activity.data[object] with Object.normalize(acitivty) to benefit from preloading

Fix unclosed ` and put synopsis into a code block in pleroma.emoji mix task docs

See merge request pleroma/pleroma!1084

task docs

Use `User.get_cached*` everywhere

See merge request pleroma/pleroma!1021

Feature/826 healthcheck endpoint

Closes #826

See merge request pleroma/pleroma!1083

Remove finmoji and add a way to download emojis in packs

Closes #817 and #821

See merge request pleroma/pleroma!1073

differences_in_mastoapi_responses.md: `content_type` parameter of post submission

See merge request pleroma/pleroma!1081

[#923] Refactored OAuthController#authorize

See merge request pleroma/pleroma!1080