Feature/arango node query

[pxp928]

Description of the PR

initial implementation of the node query for arangoDB (currently only implemented for package and source nodes). Will continue with the implementation once the maintainer's feedback is received.

PR Checklist

• All commits have a Developer Certificate of Origin (DCO) -- they are generated using -s flag to git commit.
• All new changes are covered by tests
• If GraphQL schema is changed, make generate has been run
• If collectsub protobuf has been changed, make proto has been run
• All CI checks are passing (tests and formatting)
• All dependent PRs have already been merged

[jeffmendoza]

Looks good. I see this logic is somewhat copied from the similar funcs in the inmem backend. We use the filter there for a lot of operations, but not here. Will we be doing more refactoring to use it?