feat: initial feature-flagged, new autocompleter. Now lazy loaded on first use MONGOSH-2036

[lerouxb]

In addition to now lazy loading mongodb-ts-autocomplete, I previously forgot that the tests won't run for the new one unless you specify USE_NEW_AUTOCOMPLETE=true.

I fixed the tests now, but it does highlight some subtle changes between the new design and the old. Notably with the typescript way we only autocomplete for collections that are known to exist, so we can't autocomplete db.doesNotExistYet.insertOne( which is a valid use case for creating a new collection. In probably all other instances this new behaviour is arguably an improvement because if you typed out a collection name that does not exist then not getting autocomplete results is a powerful hint that you made a mistake.

Furthermore the new autocomplete does not take into account server version or capabilities (yet), so things like getShardDistribution autocompletes for every collection and db.watch autocomplete for every database.

And finally mongodb-ts-autocomplete does not support connections that aren't connected. It expects objects like db to be real and to be able to list databases and collections and get collection schemas. We can probably tweak it in future so you can get a partial experience, but for now I'm not calling it in the noDb scenario. It is still feature flagged after all.

[addaleax]

--nodb does not directly imply that db is inaccessible, e.g. you can do

$ mongosh --nodb
[...]
> db = connect(process.env.CLUSTER);

to basically get the same behavior as mongosh $CLUSTER

[lerouxb]

Do you have an idea of a better thing to check?

[addaleax]

You'd have to check what the methods on getAutocompletionContext() return (/whether they return), I'd say

[lerouxb]

I removed the code from here. Will add it to mongodb-ts-autocomplete separately

[lerouxb]

and added mongodb-js/devtools-shared#542