Aioimaplib

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- [aiolib] idle : added an idle_waiter for an event based idle loop

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- [aiolib] do not filter exists line for examine command
- [aiolib] idle : wait for the end of data frame before pushing into the queue
- [test] imapserver enhancements : accepts sequence sets/returns UID when fetch by uid

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- [aiolib] idle : added loop methods

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- [aiolib][fix] it's up to the user to send idle DONE

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- [aiolib] timeout for idle of 29 minutes + timeout of wait_server_push doesn't raise TimeoutException

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- [aiolib] added timeout for wait_server_push of 29 minutes
- [aiolib] Remove imap's Continuation from server when connection is idled. Provide imapserver.wait_state to wait for idle in tests
- [test][refactor] Replace WithIMapServer inheritance by mixin combinations between ClockTestCase/TestCase and WithIMapServer
- [test] Allow to send a html email
- [fix] handling untagged responses with noop async command