[CP-141] Added accounts functions. (#100)

* [CP-141] Added `accounts` functions.

This PR only adds the CRUD for account, the next will add Account Privileges (if really needed).
See TODOs in the code, these needs to be resolved in this PR.

* Fixed typo

* Fixed gRPC Gateway REST urls (iam --> account).

* Added privileges (as []string) to account, as RO property

* Update proto/qdrant/cloud/account/v1/account.proto

Co-authored-by: Toni Reina <toni.reina@qdrant.com>

* Addressed feedback / resolved TODOs

* Review comments addressed.

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Co-authored-by: Toni Reina <toni.reina@qdrant.com>

Author: Robert-Stam