Add errors for nonexistend include directory or missing path dependency

[mrogenmoserTT]

No description provided.

[fischeti]

I think we already talked about this, and I just wanted to write down a current issue:

Bender does not consider targets correctly. For instance, an include directory that is guarded by a target and does not exists (yet):

  - target: missing_folder
    include_dirs:
      - missing_folder/include
    files:
      - missing_folder/my_module.sv

throws an error at the moment even if missing_folder is not specified as a target

[mrogenmoserTT]

I adjusted the internals to only error if the missing include_directory is actually required 👍

[fischeti]

I think it should work now as intended. I still get an error from the snitch_cluster dependency due to this:

https://github.com/pulp-platform/snitch_cluster/blob/5b2fccd96c42812774c20ab2f9b811e164809789/Bender.yml#L38

Whi can/should be fixed in the snitch cluster🤓

[micprog]

As far as I understand, there is no inherent harm in including a non-existent directory for any downstream tool, although it is bad practice, unlike if a file doesn't exist. Therefore, I think it makes the most sense to convert this error into a warning, not an error.