Add a SPI that would allow to add metadata to components

There's currently no way to add metadata to a component detail (see https://github.com/Talend/component-runtime/blob/master/component-server-parent/component-server/src/main/java/org/talend/sdk/component/server/front/ComponentResourceImpl.java#L431). It would be interesting to add a SPI that would allow developers to enrich those metadata with custom key/value.

My current use case would be to flag component as TDP functions, by giving some information needed by the application which will consume the list of available functions through the component-server. A TDP function is a usual processor, with additional metadata information.