Since uploading a file is done on the TelegramClient, and the
InputFiles are only valid for a short period of time, it only
makes sense to cache the sent media instead (which should not
expire). The problem is the MD5 is only needed when uploading
the file.
The solution is to allow this method to check for the wanted
cache, and if available, return an instance of that, so to
preserve the flexibility of both options (always InputFile,
or the cached InputPhoto/InputDocument) instead reuploading.
Caching the inputFile values would not persist accross several
days so the cache was nearly unnecessary. Saving the id/hash of
the actual inputMedia sent is a much better/persistent idea.
This removes the need for a .clear_cache() method as now files
are identified by their MD5 (which needs to be calculated
always) and their file size (to make collisions even more
unlikely) instead using the file path (which can now change).
Server salts change every 30 minutes after all, so keeping them
in the long-term storage session file doesn't make much sense.
Saving the layer doesn't make sense either, as it was only used
to know whether to init connection or not, but it should be done
always.
There are still a few things to change, like cleaning up the
code and actually caching the entities as a whole (currently,
although the username/phone/name can be used to fetch their
input version which is an improvement, their full version
needs to be re-fetched. Maybe it's a good thing though?)
Some bug was causing an infinite lock due to the entity
database failing with InputPeerSelf, since adding a full
entity to the database wasn't disallowing self, and so
wasn't utils get_peer_id. Although last commit fixed that,
just in case, swallow errors there.
After some discussion, storing the session ID is not needed at all.
It can always start off as a new random 8-byte-long number, also
restarting the sequence number at 0. This should prevent some seqno
too low errors.
Also, saving the time offset could cause more trouble than fixing
them, so that has also been removed.
