Allow topic and service to construct messages from description files

[mjcarroll]

🦟 Bug fix

The current implementation allows for additional messages to be read from these files, it was just not properly configured for the files to be accessible.

Summary

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)
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[mjcarroll]

@osrf-jenkins retest this please

[shameekganguly]

LGTM, thanks!

[caguero]

How are you testing it? Is this example easily backportable?

https://gazebosim.org/api/msgs/10/messagegeneration.html

[mjcarroll]

How are you testing it? Is this example easily backportable?

I can add a test. Since this is already targeting gz-msgs9 (garden), I don't think there is a reason to backport it any further?

[caguero]

How are you testing it? Is this example easily backportable?

I can add a test. Since this is already targeting gz-msgs9 (garden), I don't think there is a reason to backport it any further?

I mean the example from gz-msgs10 to gz-msgs9. I think we could use this example to test it.

[mjcarroll]

I think we could use this example to test it.

Added an INTEGRATION_descriptors test with a few more descriptors configurations to exercise this.

[codecov]

Codecov Report

Attention: Patch coverage is 95.83333% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 96.16%. Comparing base (29cfe33) to head (fbe8627).

Files	Patch %	Lines
src/Factory.cc	95.83%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           gz-msgs9     #428      +/-   ##
============================================
+ Coverage     95.57%   96.16%   +0.59%     
============================================
  Files            10       10              
  Lines          1062     1069       +7     
============================================
+ Hits           1015     1028      +13     
+ Misses           47       41       -6     

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[mjcarroll]

@osrf-jenkins retest this please