http_security_plug.ex: Fix non-proxied media

See merge request pleroma/pleroma!2610

Docs: Attachement limitations in MastoAPI differences

See merge request pleroma/pleroma!2607

fix unused var warning in streamer test

See merge request pleroma/pleroma!2612

Add blob: to connect-src CSP, fixes #1827

Closes #1827

See merge request pleroma/pleroma!2608

Fix argument error in streamer

See merge request pleroma/pleroma!2609

Database vacuum mix task

See merge request pleroma/pleroma!2599

`Repo.exists` can't use `nil` as it is unsafe.
Use parent object instead of activity because currently Announce activity's context is null.

Fix relay repeat notification

See merge request pleroma/pleroma!2590

Fix profile emojis bypassing mediaproxy and harden CSP

Closes #1810

See merge request pleroma/pleroma!2596

get-packs for local generated pack

Closes #1557

See merge request pleroma/pleroma!2604

Validate actor type

See merge request pleroma/pleroma!2593

Update installation guides

See merge request pleroma/pleroma!2603

Fix minor spelling error

See merge request pleroma/pleroma!2598

Update AdminFE build, re-enables emoji packs

See merge request pleroma/pleroma!2597

- Directives are now separated with ";" instead of " ;",
according to https://www.w3.org/TR/CSP2/#policy-parsing
the space is optional
- Use an IO list, which at the end gets converted to a binary as
opposed to ++ing a bunch of arrays with binaries together and joining
them to a string. I doubt it gives any significant real world advantage,
but the code is cleaner and now I can sleep at night.
- The static part of csp is pre-joined to a single binary at compile time.
Same reasoning as the last point.

Also use atom keys in emoji maps instead of binaries

Closes #1810

They were not properly cleaned later and caused trouble for another tests

Fix ObjectView calling into strange functions

Closes #1807

See merge request pleroma/pleroma!2580

Notification performance fixes

See merge request pleroma/pleroma!2595

ActivityPub: Change ordering to `nulls last` in favorites query

See merge request pleroma/pleroma!2594

This makes it use our existing index and speeds up the query.

Fix favorites query performance

See merge request pleroma/pleroma!2591