Get links on agent id locally

[zippy]

PR summary

This PR adds:

• an optimization of not querying the DHT for get links requests that are placed on a node's own agent id because we must be responsible for holding that part of the DHT.

Note this does not include the optimization for not querying for other links that we are currently holding because sim2h currently does not tell us to stop holding things as neighborhoods change so we always need to check the dht for other links lest what we are holding be out-of-date.

testing/benchmarking notes

( if any manual testing or benchmarking was/should be done, add notes and/or screenshots here )

followups

( any new tickets/concerns that were discovered or created during this work but aren't in scope for review here )

changelog

• if this is a code change that effects some consumer (e.g. zome developers) of holochain core, then it has been added to our between-release changelog with the format

- summary of change [PR#1234](https://github.com/holochain/holochain-rust/pull/1234)

documentation

• this code has been documented according to our docs checklist