[V3] Make bot send typing whilst loading cogs (#1756)

* Show bot is responsive during cog load

* Log download of Lavalink.jar event

* Fix #1709's other bug

* Reformat

* Update core_commands.py from merge

redbot/cogs/audio/__init__.py

@@ -1,6 +1,7 @@
 from pathlib import Path
 from aiohttp import ClientSession
 import shutil
+import logging
 
 from .audio import Audio
 from .manager import start_lavalink_server
@@ -8,6 +9,8 @@ from discord.ext import commands
 from redbot.core.data_manager import cog_data_path
 import redbot.core
 
+log = logging.getLogger("red.audio")
+
 LAVALINK_DOWNLOAD_URL = (
     "https://github.com/Cog-Creators/Red-DiscordBot/" "releases/download/{}/Lavalink.jar"
 ).format(redbot.core.__version__)
@@ -33,15 +36,13 @@ async def maybe_download_lavalink(loop, cog):
     jar_exists = LAVALINK_JAR_FILE.exists()
     current_build = redbot.core.VersionInfo(*await cog.config.current_build())
 
-    session = ClientSession(loop=loop)
-
     if not jar_exists or current_build < redbot.core.version_info:
+        log.info("Downloading Lavalink.jar")
         LAVALINK_DOWNLOAD_DIR.mkdir(parents=True, exist_ok=True)
-        await download_lavalink(session)
+        async with ClientSession(loop=loop) as session:
+            await download_lavalink(session)
         await cog.config.current_build.set(redbot.core.version_info.to_json())
 
-    session.close()
-
     shutil.copyfile(str(BUNDLED_APP_YML_FILE), str(APP_YML_FILE))