Integrate autoindexing into the `vaults` domain

[joshuakarp]

Specification

Once autoindexing has been implemented into js-db, this should be brought into js-polykey and integrated into the vaults domain.

Additional context

• autoindexing issue in js-db Integrate Automatic Indexing into DB js-db#1 and the corresponding PR WIP: Integrating Automatic Indexing into DB js-db#2
• usage of the vault name for creation of a vault https://gitlab.com/MatrixAI/Engineering/Polykey/js-polykey/-/merge_requests/205#note_700936060 and when enforcing uniqueness on creation https://gitlab.com/MatrixAI/Engineering/Polykey/js-polykey/-/merge_requests/205#note_692109270

Tasks

Provide support for:

1. Using the index to look up by vault name (currently, it performs a linear search over all vaults)
2. Using the index to look up by node ID from the remote field (i.e. a cloned vault that originally came from the specified node ID) - this would mean the node ID needs to be part of the metadata
3. Using the index to enforce the uniqueness constraint on vault name and to prevent duplicate vault names

[CMCDragonkai]

We're not going to do autoindexing anymore. See reasons in MatrixAI/js-db#1