Fixing bug in the annotation of variable ops.
Fixed issues found by PyLint Hi @pjannaty Can you please review this PR ? Thank you! Hi @pjannaty Can you please review this PR ? Thank you! Hi @pjannaty Can you please review this PR ? Thank you! Hi @pjannaty Can you please review this PR ? Thank you! Hi @drivanov, @pjannaty  I'm going to go ahead and close this PR, because it seems to have stalled. If you're still interested in pursing this (and responding to my comments), please feel free to reopen! Thank you!
To facilitate the conversion of variable ops (used in the experimental `disable_graph_freezing` mode) the converter annotates the graph with the shape of the variable ops.

This PR fixes the mapping between captured input names and variables so that the graph can be annotated correctly.
the problem with the previously used mapping appeared when the list `graph.internal_captures` contains the non-resource type elements. 

The unit test is provided.