No input service request from the command line

[caguero]

🦟 Bug fix

Fixes #97 and #474

Summary

This patch makes it possible to request a no input service request from the command line. Before, it was possible passing --reqtype gz.msgs.Empty but always adding the --req 'unused: true'

How to test it?

You can compile the examples, and then:

1. Launch the no-input responser:

./responser_no_input

2. Request the service using the "old" way:

gz service -s /quote --reqtype gz.msgs.Empty --reptype gz.msgs.StringMsg -r 'unused:true'

3. Use the new no-input request and verify that you still get a reply:

gz service -s /quote --reptype gz.msgs.StringMsg -r

Note that both requests should reach the responser and you should get a reply on the requester terminal:

data: "This is it! This is the answer. It says here...that a bolt of lightning is going to strike the clock tower at precisely 10:04pm, next Saturday night! If...If we could somehow...harness this lightning...channel it...into the flux capacitor...it just might work. Next Saturday night, we\'re sending you back to the future!"

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[caguero]

@osrf-jenkins run tests please

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.83%. Comparing base (eac2e69) to head (7b1e4de).
Report is 8 commits behind head on gz-transport13.

Additional details and impacted files

@@                Coverage Diff                 @@
##           gz-transport13     #487      +/-   ##
==================================================
+ Coverage           87.69%   87.83%   +0.14%     
==================================================
  Files                  59       59              
  Lines                5704     5706       +2     
==================================================
+ Hits                 5002     5012      +10     
+ Misses                702      694       -8     

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[azeey]

I think you need to merge from gz-transport13 to fix the ABI checker issues. This repo doesn't require having the branch up-to-date to merge, but we can enable it if we want.