RTDB emulator v4.6.1

[jmwski]

Description

Contains a fix for a longstanding emulator bug that caused #2734

Scenarios Tested

Ran npm install and node lib/bin/firebase.js emulators:start --only database

curl -H "Authorization: Bearer owner" -X PUT -d @bad.rules.json localhost:9000/.settings/rules.json?ns=test-ns

Where bad.rules.json contains the example rules from the issue:

{
  "rules": {
      "$offering_id": {
          ".validate": "newData.hasChildren(['timestamp', 'text']"
      }
  }
}