add access to ToolchainCMD MetaData

- temporarily add clarin repository to access bindings dependency (remove when bindings will be at Maven Central)
- add bindings dependency
- add Source into MetaData for backward compatibility with existing TCF that might contain this element
- deprecate Source and MetaDataItem components of MetaData
- add Services with ToolchainCMD into MetaData according to latest changes in TCF MetaData defenition
- add into one of the input test files the Services element to test the access to ToolchainCMD