ParserConfig: add ToElementUseIncludeTag policy

[scpeters]

🦟 Bug fix

Part of #881 and should be reviewed before the 12.4.0 release.

Summary

This adds a new policy to the ParserConfig class to replace
the boolean parameter in the Model, Root, and World
ToElement methods that specifies whether include tags should
be used or the complete model. ParserConfig objects are then
passed to the ToElement methods instead of the bool,
allowing the ParserConfig to be used in additional
sdf::initFile API calls. This changes only unreleased
parts of the API, which is permitted.

I don't love the SetToElementUseIncludeTag and ToElementUseIncludeTag method names, but it's the best I could think of on short notice. Suggestions are welcome.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• 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.

[codecov-commenter]

Codecov Report

Merging #887 (b0adcd2) into sdf12 (8733d08) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head b0adcd2 differs from pull request most recent head 91f01cc. Consider uploading reports for the commit 91f01cc to get more accurate results

@@           Coverage Diff           @@
##            sdf12     #887   +/-   ##
=======================================
  Coverage   88.16%   88.16%           
=======================================
  Files         100      100           
  Lines       14629    14634    +5     
=======================================
+ Hits        12897    12902    +5     
  Misses       1732     1732           

Impacted Files	Coverage Δ
src/Model.cc	92.72% <100.00%> (ø)
src/ParserConfig.cc	100.00% <100.00%> (ø)
src/Root.cc	95.12% <100.00%> (ø)
src/World.cc	95.02% <100.00%> (ø)

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[nkoenig]

@scpeters the use of ParserConfig seems a bit odd here. The ToElement functions are not 'parsing' and the other functions in the ParserConfig class don't seem relevant to the ToElement function.

I can create a new class that is tailored for ToElement conversion.

[azeey]

@scpeters and I were just talking about this yesterday. I had mentioned to him that there was precedent for using PaserConfig as a general data structure for configuring the libsdformat library. Looking at the functions closely, I don't think I was correct. It looks like everything there (except to UseIncludeTag) is pertinent the internal parsing logic, so creating a new class for configuring outputs makes sense.

[scpeters]

that sounds fine to me

[osrf-triage]

This pull request has been mentioned on Gazebo Community. There might be relevant details there:

https://community.gazebosim.org/t/new-ignition-releases-2022-04-13-fortress-edifice/1367/1