Actually create a bridge desc manager and call install_bridge_desc_provider

As prompted by @nickm on irc. This is part of #69 (closed) (and this ticket may be a dupe I guess...)

assigned to @Diziet

added Doing label

changed milestone to %Arti 1.1.0: Anticensorship ready

This turns out to be a bit troublesome.

The difficulty is that Store, the sqlite database that BridgeDescMgr uses, is buried within DirMgr. But there may not even be a DirMgr, since we support a replaceable DirProvider via DirProviderBuilder.

Logically, a replaced DirProvider ought to still leave us with a Store for other purposes. But we don't want to make the whole of the Store part of our stable API.

I propose therefore to do this:

• Make a public trait DirMgrStore which has the private Store as a supertrait. (So DirMgrStore is sealed.)
• Make DynStore use dyn DirMgrStore. There might have to be DynCast or something; at least there will have to be an as_ref impl.
• Move creating the Store to TorClient and have DirProviderBuilder take a DynStore.
• Change BridgeDescMgr to take the things it needs directly, replacing new_with_dirmgr with new.

I'm +1 on this plan as I understand it.

(@eta has also touched the dirmgr code and may have suggestions too.)

This makes sense to me! This should help out future refactorings of the downloading code, too; currently a lot of that takes a DirMgr where it could just take a Store instead, so it'll be even nicer if that's a more abstract trait.

mentioned in commit Diziet/arti@92939439

mentioned in merge request !850 (merged)

mentioned in merge request !851 (merged)

mentioned in merge request !852 (merged)

mentioned in commit 88caacfb

closed with merge request !852 (merged)