Would it be possible to add support for contexts using the old build api:

My use case is as following: I've a deploy which is manually invoked through the api. Each deploy has some different set of parameters hence I must use the old api (since I require the use of build_parameters). I would like to store env vars in contexts instead of sending them via the build parameters since it is more organized this way (I would just invoke the api and tell it which context name to use). Also, I'm using the old api since it supports specifying the config file as a parameters which is very convenient when testing

CCI-I-1088