hc hash --property

[lucksus]

PR summary

Add option "property" to hc hash that sets DNA properties for hash calculation.

USAGE:
    hc hash [OPTIONS]

OPTIONS:
    -p, --path <path>               Path to .dna.json file [default: dist/<dna-name>.dna.json]
    -x, --property <property>...    Property (in the from 'name=value') that gets set/overwritten before calculating
                                    hash

Like so:

[nix-shell:~]$ hc hash --path identity-manager.dna.json --property agent_id=HcSc82gf923hd
Reading DNA from QmZUhssczL8RdBUjKLrtFyV9co2BCHubmJTdj4oeMaUYki.dna.json
DNA Hash: QmWPhCUU3Gib9kTHs2gtiD1VFnwrvqX1zcKFf1WNNnD6mk

followups

Use this in Holoscape to be able to detect installed instances even if they were installed with specific/unique properties (such as identity manager).

changelog

Please check one of the following, relating to the CHANGELOG-UNRELEASED.md

• this is a code change that effects some consumer (e.g. zome developers) of holochain core so it is added to the CHANGELOG-UNRELEASED.md (linked above), with the format - summary of change [PR#1234](https://github.com/holochain/holochain-rust/pull/1234)
• this is not a code change, or doesn't effect anyone outside holochain core development

documentation

• this code has been documented according to our docs checklist

[StaticallyTypedAnxiety]

You might be able to shorten this by :
let equal = "=";
let equal_sign= property_string.find(equal).unwrap_or_else(|| Err(err_msg(format!(
"Can't parse property: {}",
property_string
))))?
let (name,value) = property_string.split_at(equal);
map.insert(name,serde_json::Value::String(value.trim_start_matches(equal )))