I had encountered some problems during rendering which looked like the displacement wasn't being applied correctly. I had some trouble figuring out why it doesn't happen always, but finally realized that rendering SVG icons takes a different code path than rendering raster icons. My current workaround of using a certain kind of AnchorPoint instead of a correct one with an appropriate Displacement works, but is so hideously ugly that I'd prefer having things work as they should.

This PR fixes the order of transformations in org.geotools.renderer.lite.StyledShapePainter IconStyle2D branch.
As documented in org.geotools.api.style.Graphic.getDisplacement, the displacement should happen after rotation. The GraphicStyle2D branch seems to have it already correct.

This PR also adds some tests to the raster branch (ExternalGraphicTest) to ensure the already correct behavior there when AnchorPoint, Rotation and Displacement are all being used. Another test in DrawTest is added to reproduce the actual bug and verify the fix.

The expected images (under test-data) at least in my opinion look correct, but please do let me know if I have thoroughly misunderstood something. Also please let me know if you need anything more from this PR.

Checklist

• I have read the contribution guidelines.
• I have sent a Contribution Licence Agreement (not required for small changes, e.g., fixing typos in documentation).
• First PR targets the main branch (backports managed later; ignore for branch specific issues).
• Avoid Java 9+ split packages.
• All the build checks are green (see automated QA checks).

For core and extension modules:

• New unit tests have been added covering the changes.
• Documentation has been updated (if change is visible to end users).
• There is an issue in GeoTools Jira (except for changes not visible to end users).
• Commit message(s) must be in the form [GEOT-XYZW] Title of the Jira ticket.
• Bug fixes and small new features are presented as a single commit.
• The commit targets a single objective (if multiple focuses cannot be avoided, each one is in its own commit, and has a separate ticket describing it).