Configure a list of channels from which to pull messages.

[abul4fia]

Instead of providing a single channel from which to pull messages, it should be possible to specify a list. Unfortunately, this idea implies adding more configuration for the following:

• Each channel or group can have its own settings for maximum number of messages, maximum number of days to go back, whether to delete messages once they are downloaded, etc.
• It should be possible for each message source to be identified in the information sent to Logseq, for example in the form of tags on the messages. Ideally, it should be configurable how to include that information (additional format string for the block format, for example) and channel names should be part of the configuration (since Teletolo only knows their IDs).