Time entire pipeline end-to-end

[emersonknapp]

Description

As a user, I can get the time the entire pipeline takes to complete, so that I can make informed decisions as to whether or not my application has any inefficiencies

Related Issues

Part of https://github.com/ros-tooling/cross_compile/issues/205

Completion Criteria

• The tool outputs the time taken for the entire cross-compile pipeline into a uniquely named file under cc_internals/

Implementation Notes / Suggestions

• Suggestion: maybe use a python context __enter__ / __exit__ construct for timers

Testing Notes / Suggestions

• Unit test for any new functions/objects
• End-to-end test should check for output file and some bit of its content, at least