Bots should not be considered when auto-naming rooms

[alexgleason]

Steps to reproduce:

• Start a message with an individual. I'll call them "Paul".
• Title of the room is Paul
• Add Giphy integration
• Room becomes renamed to Paul and giphy
• Remove Giphy
• Room is named Paul again but the icon reverts to a "P" instead of Paul's avatar

Expected outcome:

• Start a message with Paul
• Add Giphy integration
• The room preserves the name Paul because Giphy is a bot. The room preserves Paul's avatar

[ara4n]

I've split out the avatar bug; meanwhile this is really a 'Bots really shouldn't be considered when naming rooms' bug

[ara4n]

Therefore we need a convention for actually detecting which users are bots, so clients can hide them appropriately in situations like this. Calculating names serverside could help.

[alexgleason]

I think this would require the spec being changed? My first thought was to detect if a bot was the result of integrations and then display it differently on the front-end, but this would be difficult to make persistent.

I imagine you could preface all bot usernames with bot_ or something. But if we're going through the trouble of trying to establish a standard for this, I think we may as well send data about it through JSON instead. Maybe is bot key on users that can be true or false.

[uhoreg]

Alternatively, it might be useful to be able to configure a room to only consider certain accounts (or ignore certain accounts) when naming the room, which could be useful when chatting with someone with multiple accounts (or even if you yourself have multiple accounts). For example, if I have a DC room with matthew:matrix.org, matthew2:matrix.org, matthew:arasphere and uhoreg_test:matrix.org, I would probably want the room to be just called "Matthew", rather than "Matthew, Evil Matthew, Matthew, and uhoreg test" (or whatever it would name the room in that case).

Probably somewhat related to #725.