Special cases of `node.context.*`

migrate node.context.currentSite to eel helper to fetch site entity
migrate node.context.workspace to eel helper to fetch workspace, but attention, the workspace api in fusion also changed.
warn if anything else is accessed by node.context.*
while the renderingMode has a basic migration via https://github.com/neos/rector/pull/22, but the not all things are migrated currently
- node.context.workspace.name == 'live' -> !renderingMode.isEdit
- node.context.workspace.personalWorkspace -> renderingMode.isEdit
- node.context.currentRenderingMode.* -> renderingMode.*

neos / rector