Use .schema to dump from sqlite

This has the following effects:

- Don't wrap the schema in a transaction
- `CREATE VIRTUAL TABLE` for full text search, which means we don't have
  to do `PRAGMA writable_scshema=...`
- Don't insert initial values for stream positions and similarly locked
  things

Both of these seem to better match the sqlite full schema dump we have
in the source tree.

Also use `--indent` to produce something that's more human readable.

```
$ diff dump/sqlite-{dump,schema}-sorted
6,7d5
< BEGIN TRANSACTION;
< COMMIT;
287a286,287
> CREATE VIRTUAL TABLE event_search USING fts4 ( event_id, room_id, sender, key, value )
> CREATE VIRTUAL TABLE user_directory_search USING fts4 ( user_id, value )
289a290
> /* event_search(event_id,room_id,sender,"key",value) */;
291,300d291
< INSERT INTO appservice_stream_position VALUES('X',0);
< INSERT INTO event_push_summary_last_receipt_stream_id VALUES('X',0);
< INSERT INTO event_push_summary_stream_ordering VALUES('X',0);
< INSERT INTO federation_stream_position VALUES('events',-1,'master');
< INSERT INTO federation_stream_position VALUES('federation',-1,'master');
< INSERT INTO schema_compat_version VALUES('X',72);
< INSERT INTO sqlite_schema(type,name,tbl_name,rootpage,sql)VALUES('table','event_search','event_search',0,'CREATE VIRTUAL TABLE event_search USING fts4 ( event_id, room_id, sender, key, value )');
< INSERT INTO sqlite_schema(type,name,tbl_name,rootpage,sql)VALUES('table','user_directory_search','user_directory_search',0,'CREATE VIRTUAL TABLE user_directory_search USING fts4 ( user_id, value )');
< INSERT INTO stats_incremental_position VALUES('X',1);
< INSERT INTO user_directory_stream_pos VALUES('X',1);
302,304d292
< PRAGMA foreign_keys=OFF;
< PRAGMA writable_schema=OFF;
< PRAGMA writable_schema=ON;
307a296
> /* user_directory_search(user_id,value) */;
```

scripts-dev/make_full_schema.sh

@@ -147,7 +147,7 @@ python -m synapse.app.homeserver --generate-keys -c "$SQLITE_CONFIG"
 
 # Make sure the SQLite3 database is using the latest schema and has no pending background update.
 echo "Running db background jobs..."
-synapse/_scripts/update_synapse_database.py --database-config --run-background-updates "$SQLITE_CONFIG"
+synapse/_scripts/update_synapse_database.py --database-config "$SQLITE_CONFIG" --run-background-updates
 
 # Create the PostgreSQL database.
 echo "Creating postgres database..."
@@ -185,7 +185,7 @@ sqlite3 "$SQLITE_DB" <<< "$SQL"
 psql "$POSTGRES_DB_NAME" -w <<< "$SQL"
 
 echo "Dumping SQLite3 schema to '$OUTPUT_DIR/$SQLITE_FULL_SCHEMA_OUTPUT_FILE'..."
-sqlite3 "$SQLITE_DB" ".dump" > "$OUTPUT_DIR/$SQLITE_FULL_SCHEMA_OUTPUT_FILE"
+sqlite3 "$SQLITE_DB" ".schema --indent" > "$OUTPUT_DIR/$SQLITE_FULL_SCHEMA_OUTPUT_FILE"
 
 echo "Dumping Postgres schema to '$OUTPUT_DIR/$POSTGRES_FULL_SCHEMA_OUTPUT_FILE'..."
 pg_dump --format=plain --no-tablespaces --no-acl --no-owner $POSTGRES_DB_NAME | sed -e '/^--/d' -e 's/public\.//g' -e '/^SET /d' -e '/^SELECT /d' > "$OUTPUT_DIR/$POSTGRES_FULL_SCHEMA_OUTPUT_FILE"