make robot only require toolchain definitions to resolve dependencies with subtoolchains

[boegel]

Currently, the --robot implementation will only resolve dependencies via a subtoolchain if the matching easyconfig file is available in the robot search path (even if the corresponding module is available already).

However, I don't think there's a strict need for it, it should suffice that just the easyconfigs that define the toolchain are available, since that's sufficient to figure out the subtoolchains to consider (w.r.t. versions).

Once the subtoolchains are known, available modules can be sufficient to resolve a dependency via a subtoolchain (unless there are other aspects that require the easyconfigs to be available, e.g. the use of HierarchicalMNS which requires an easyconfig file to determine the full module name).

Thoughts @ocaisa?

[ocaisa]

This approach also wouldn't work if modaltsoftname was used in the (now unparsed) dep easyconfig as the module name wouldn't be correct.

[paulmelis]

To clearify, is this bug applicable only when --robot is used?

[boegel]

@paulmelis Hmm, good question... It's actually the process of finding modules for each of the dependencies, which is not exactly the same as --robot (which does more than that).

@ocaisa I hope to find time to try and fix this bug soon. You've been doing quite a bit of work related to subtoolchains recently, any idea how difficult this would be?