Add repo specific issue templates

[azeey]

Summary

Override the org level issue templates in order to make the issue templates more specific to this repo. This is currently just a copy of the files from https://github.com/ignitionrobotics/.github, but we are planning to remove the GUI/Rendering section from the issue templates there.

Note, I had to copy both files in ISSUE_TEMPLATES even though we only need to override bug_report.md because Github will not use the org level defaults if it finds any files in the repo's ISSUE_TEMPLATES directory.

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• 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.

[codecov]

Codecov Report

Merging #1461 (5be2dd6) into ign-gazebo3 (97a87c3) will decrease coverage by 43.21%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##           ign-gazebo3    #1461       +/-   ##
================================================
- Coverage        77.88%   34.67%   -43.22%     
================================================
  Files              250       31      -219     
  Lines            14378     1993    -12385     
================================================
- Hits             11198      691    -10507     
+ Misses            3180     1302     -1878     

Impacted Files	Coverage Δ
src/systems/detachable_joint/DetachableJoint.cc
...lude/ignition/gazebo/components/PerformerLevels.hh
...lude/ignition/gazebo/components/DetachableJoint.hh
.../ignition/gazebo/components/PhysicsEnginePlugin.hh
include/ignition/gazebo/Link.hh
src/SdfEntityCreator.cc
src/Barrier.cc
include/ignition/gazebo/components/Altimeter.hh
.../gui/plugins/transform_control/TransformControl.cc
include/ignition/gazebo/components/Lidar.hh
... and 271 more

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