5202 make understand json

[maxgrossman]

adds new function loadMapFromJSONString to the MapIoJs.h.
this gets used in the translation server, allowing it to accept json flavor osm data.

[brianhatchl]

I have seen this cucumber test failure a few times since #5249 was merged.

[](https://jenkins.nomedev.com/blue/organizations/jenkins/Hootenanny/detail/PR-5261/3/pipeline/#step-89-log-22)[](https://jenkins.nomedev.com/blue/organizations/jenkins/Hootenanny/detail/PR-5261/3/pipeline/#step-89-log-23)[](https://jenkins.nomedev.com/blue/organizations/jenkins/Hootenanny/detail/PR-5261/3/pipeline/#step-89-log-24)[](https://jenkins.nomedev.com/blue/organizations/jenkins/Hootenanny/detail/PR-5261/3/pipeline/#step-89-log-25)Unable to find visible link or button "Add Reference Dataset" (Capybara::ElementNotFound)
./features/step_definitions/custom_steps.rb:456:in `/^I press "([^"]*)"$/'
./features/support/hooks.rb:43:in `block in <top (required)>'
features/paste_attributes.feature:22:in `And I press "Add Reference Dataset"'

The failure is intermittent, so I've just re-run the jenkins job 🤷

[brianhatchl]

Seems ✌️ legit 🥈 🛑 🕺

[bmarchant]

Looks good.