Update the adaptor picklist with an @local option to support local adaptor dev in lightning

[christad92]

@stuartc I have (almost) implemented support for local/monorepo adaptors in the worker in #808

tl;dr: if lightning sets the adaptor version to @local on a given step, the worker will try to load it from the monorepo

This has been useful for collections so I just ploughed on with it

Edit: that's merged. So all we need to do is update the picklist with an @local option and we can support local adaptor dev in lightning

Originally posted by @josephjclark in #905

We need to add a flag that allows users to the turn off the local option via the environment variables.