[Feature request] Provide a manifest.json selection option

[Lensual]

#78

1. Provide a manifest.json selection option
2. Online edit
3. Run as edited temporary manifest.json online

[cyfyifanchen]

With the latest update, manifest.json is no longer available. Instead tweak ./agents/property.json and swap the values in from graphNameDefault in config.go.

The next step is making the values as options that can be selected on the UI.