[Astra DB] Explicit projection when reading from Astra DB

[hemidactylus]

In view of upcoming changes in the Astra DB Data API, this PR explicitly sets a projection every time a find command is executed, in order to ensure all necessary fields of the document are returned by the API.

[CLAassistant]

All committers have signed the CLA.

[hemidactylus]

@erichare FYI

[julian-risch]

Hello @hemidactylus and thank you for opening this pull request! 🙂Could you please share some more context regarding upcoming changes in the Astra DB Data API? Any links to documentation or release notes? And could you share how you tested the changes? Thank you!

[masci]

Thank you! Merging and drafting a new release

[hemidactylus]

Hello, @julian-risch ! At this stage, the plans to drop the $vector field from the default projection are just plans with no defined timeline. The reasoning is that returning that field often bloats the response for no reason, as most applications do not actually need the very vector back when doing reads.
And since it's a good practice to specify a projection explicitly, this was a good enough reason in my view to do so in this code, making the read path resilient against changes in the API.
(reference: this docs page implies that "special" fields are not guaranteed to be included in the default projection).

As for testing ... I have to admit that given the simplicity of the change I just ran the relevant parts of the new code manually on a handmade collection, to make sure there were no trivial issues, and that was it.

Also @masci grazie per il merge ;)

[julian-risch]

Thank you @hemidactylus and @masci !