core: support batch sending in groups, batch introductions; send recent message history to new members (#3519)

* core: batch send stubs, comments

* multiple events in ChatMessage and supporting types

* Revert "multiple events in ChatMessage and supporting types"

This reverts commit 9b239b26ba.

* schema, refactor group processing for batched messages

* encoding, refactor processing

* refactor code to work with updated schema

* encoding, remove instances

* wip

* implement batching

* batch introductions

* wip

* collect and send message history

* missing new line

* rename

* test

* rework to build history via chat items

* refactor, tests

* correctly set member version range, dont include deleted items

* tests

* fix disappearing messages

* check number of errors

* comment

* check size in encodeChatMessage

* fix - don't check msg size for binary

* use builder

* rename

* rename

* rework batching

* lazy msg body

* use withStoreBatch

* refactor

* reverse batches

* comment

* possibly fix builder for single msg

* refactor batcher

* refactor

* dont repopulate msg_deliveries on down migration

* EncodedChatMessage type

* remove type

* batcher tests

* add tests

* group history preference

* test group link

* fix tests

* fix for random update

* add test testImageFitsSingleBatch

* refactor

* rename function

* refactor

* mconcat

* rename feature

* catch error on each batch

* refactor file inv retrieval

* refactor gathering item forward events

* refactor message batching

* unite migrations

* move files

* refactor

* Revert "unite migrations"

This reverts commit 0be7a3117a.

* refactor splitFileDescr

* improve tests

* Revert "dont repopulate msg_deliveries on down migration"

This reverts commit 2944c1cc28.

* fix down migration

---------

Co-authored-by: Evgeny Poberezkin <2769109+epoberezkin@users.noreply.github.com>

src/Simplex/Chat/Help.hs

@@ -155,7 +155,8 @@ groupsHelpInfo =
       "",
       green "Group chat preferences:",
       indent <> highlight "/set voice #<group> on/off         " <> " - enable/disable voice messages",
-      -- indent <> highlight "/set files #<group> on/off         " <> " - enable/disable files and media (other than voice)",
+      indent <> highlight "/set files #<group> on/off         " <> " - enable/disable files and media (other than voice)",
+      indent <> highlight "/set history #<group> on/off       " <> " - enable/disable sending recent history to new members",
       indent <> highlight "/set delete #<group> on/off        " <> " - enable/disable full message deletion",
       indent <> highlight "/set direct #<group> on/off        " <> " - enable/disable direct messages to other members",
       indent <> highlight "/set disappear #<group> on <time>  " <> " - enable disappearing messages with <time>:",