Bridge should wait on startup if a flood error is reported

[Half-Shot]

During startup after presumably having issues with the bridge: Telethon raised an exception about needing to wait before the client could sign in.

Rather than waiting for the flood time, the bridge simply exited and restarted leading to a longer required wait time.

The bridge should probably just wait out the required time reported in FloodWaitError and then try to start, rather than crashlooping and making the problem worse.

[2022-09-12 13:18:47,894] [CRITICAL@mau.init] Unexpected error in main event loop
Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/mautrix/util/program.py", line 219, in _run
    self.loop.run_until_complete(self.start())
  File "/usr/lib/python3.9/asyncio/base_events.py", line 647, in run_until_complete
    return future.result()
  File "/usr/lib/python3.9/site-packages/mautrix_telegram/__main__.py", line 133, in start
    await super().start()
  File "/usr/lib/python3.9/site-packages/mautrix/bridge/bridge.py", line 228, in start
    await super().start()
  File "/usr/lib/python3.9/site-packages/mautrix/util/program.py", line 253, in start
    await asyncio.gather(*(self.startup_actions or []))
  File "/usr/lib/python3.9/site-packages/mautrix_telegram/bot.py", line 105, in start
    await self.client.sign_in(bot_token=self.token)
  File "/usr/lib/python3.9/site-packages/telethon/client/auth.py", line 368, in sign_in
    result = await self(request)
  File "/usr/lib/python3.9/site-packages/telethon/client/users.py", line 30, in __call__
    return await self._call(self._sender, request, ordered=ordered)
  File "/usr/lib/python3.9/site-packages/telethon/client/users.py", line 84, in _call
    result = await future
telethon.errors.rpcerrorlist.FloodWaitError: A wait of 20813 seconds is required (caused by ImportBotAuthorizationRequest)
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