Merge branch 'feature/account-export' into 'develop'

Add account export

Closes #847

See merge request pleroma/pleroma!2918

docs/API/pleroma_api.md

@@ -615,3 +615,41 @@ Emoji reactions work a lot like favourites do. They make it possible to react to
   {"name": "😀", "count": 2, "me": true, "accounts": [{"id" => "xyz.."...}, {"id" => "zyx..."}]}
 ]
 ```
+
+## `POST /api/v1/pleroma/backups`
+### Create a user backup archive
+
+* Method: `POST`
+* Authentication: required
+* Params: none
+* Response: JSON
+* Example response:
+
+```json
+[{
+    "content_type": "application/zip",
+    "file_size": 0,
+    "inserted_at": "2020-09-10T16:18:03.000Z",
+    "processed": false,
+    "url": "https://example.com/media/backups/archive-foobar-20200910T161803-QUhx6VYDRQ2wfV0SdA2Pfj_2CLM_ATUlw-D5l5TJf4Q.zip"
+}]
+```
+
+## `GET /api/v1/pleroma/backups`
+### Lists user backups
+
+* Method: `GET`
+* Authentication: not required
+* Params: none
+* Response: JSON
+* Example response:
+
+```json
+[{
+    "content_type": "application/zip",
+    "file_size": 55457,
+    "inserted_at": "2020-09-10T16:18:03.000Z",
+    "processed": true,
+    "url": "https://example.com/media/backups/archive-foobar-20200910T161803-QUhx6VYDRQ2wfV0SdA2Pfj_2CLM_ATUlw-D5l5TJf4Q.zip"
+}]
+```

docs/configuration/cheatsheet.md

@@ -1078,6 +1078,20 @@ Control favicons for instances.
 
 * `enabled`: Allow/disallow displaying and getting instances favicons
 
+## Pleroma.User.Backup
+
+!!! note
+    Requires enabled email
+
+* `:purge_after_days` an integer, remove backup achives after N days.
+* `:limit_days` an integer, limit user to export not more often than once per N days.
+* `:dir` a string with a path to backup temporary directory or `nil` to let Pleroma choose temporary directory in the following order:
+    1. the directory named by the TMPDIR environment variable
+    2. the directory named by the TEMP environment variable
+    3. the directory named by the TMP environment variable
+    4. C:\TMP on Windows or /tmp on Unix-like operating systems
+    5. as a last resort, the current working directory
+
 ## Frontend management
 
 Frontends in Pleroma are swappable - you can specify which one to use here.