use SQL's limit/offset pagination for nextIndex/maxCount requests (#185)

Instead of retrieving the entire list of items/characters/scores/etc. at once (and even store them in memory), use SQL's `LIMIT ... OFFSET ...` pagination so we only take what we need.

Currently only CHUNITHM uses this, but this will also affect maimai DX and O.N.G.E.K.I. once the PR is ready.

Also snuck in a fix for CHUNITHM/maimai DX's `GetUserRivalMusicApi` to respect the `userRivalMusicLevelList` sent by the client.

### How this works

Say we have a `GetUserCharacterApi` request:

```json
{
    "userId": 10000,
    "maxCount": 700,
    "nextIndex": 0
}
```

Instead of getting the entire character list from the database (which can be very large if the user force unlocked everything), add limit/offset to the query:

```python
select(character)
.where(character.c.user == user_id)
.order_by(character.c.id.asc())
.limit(max_count + 1)
.offset(next_index)
```

The query takes `maxCount + 1` items from the database to determine if there is more items than can be returned:

```python
rows = ...

if len(rows) > max_count:
    # return only max_count rows
    next_index += max_count
else:
    # return everything left
    next_index = -1
```

This has the benefit of not needing to load everything into memory (and also having to store server state, as seen in the [`SCORE_BUFFER` list](2274b42358/titles/chuni/base.py (L13)).)

Reviewed-on: Hay1tsme/artemis#185
Co-authored-by: beerpsi <beerpsi@duck.com>
Co-committed-by: beerpsi <beerpsi@duck.com>

core/data/database.py

@@ -1,11 +1,12 @@
 import logging
 import os
 import secrets
+import ssl
 import string
 import warnings
 from hashlib import sha256
 from logging.handlers import TimedRotatingFileHandler
-from typing import ClassVar, Optional
+from typing import Any, ClassVar, Optional
 
 import alembic.config
 import bcrypt
@@ -35,12 +36,20 @@ class Data:
 
         if self.config.database.sha2_password:
             passwd = sha256(self.config.database.password.encode()).digest()
-            self.__url = f"{self.config.database.protocol}+aiomysql://{self.config.database.username}:{passwd.hex()}@{self.config.database.host}:{self.config.database.port}/{self.config.database.name}?charset=utf8mb4&ssl={str(self.config.database.ssl_enabled).lower()}"
+            self.__url = f"{self.config.database.protocol}+aiomysql://{self.config.database.username}:{passwd.hex()}@{self.config.database.host}:{self.config.database.port}/{self.config.database.name}"
         else:
-            self.__url = f"{self.config.database.protocol}+aiomysql://{self.config.database.username}:{self.config.database.password}@{self.config.database.host}:{self.config.database.port}/{self.config.database.name}?charset=utf8mb4&ssl={str(self.config.database.ssl_enabled).lower()}"
+            self.__url = f"{self.config.database.protocol}+aiomysql://{self.config.database.username}:{self.config.database.password}@{self.config.database.host}:{self.config.database.port}/{self.config.database.name}"
 
         if Data.engine is MISSING:
-            Data.engine = create_async_engine(self.__url, pool_recycle=3600, isolation_level="AUTOCOMMIT")
+            Data.engine = create_async_engine(
+                self.__url,
+                pool_recycle=3600,
+                isolation_level="AUTOCOMMIT",
+                connect_args={
+                    "charset": "utf8mb4",
+                    "ssl": self.config.database.create_ssl_context_if_enabled(),
+                },
+            )
             self.__engine = Data.engine
 
         if Data.session is MISSING: