Fix Unreported: Use correct icons for pose markers in Action editor

The pose markers were confusing, as the selection state also changed
the shape of the icon.

`PMARKER_ACT` and `PMARKER_SEL` (resp. active and selected) now look
the same. There is no concept any more of an "active" pose marker, but
the icon is still there to avoid breaking add-ons that happen to use
it.

`PMARKER` (unselected) now uses the icon that previously was used for
`PMARKER_SEL`.

This way the pose markers are always visually different from scene
markers.

Pull Request: https://projects.blender.org/blender/blender/pulls/132819

release/datafiles/icons_svg/pmarker.svg

@@ -1 +1 @@
-<svg height="900" viewBox="0 0 1100 900" width="1100" xmlns="http://www.w3.org/2000/svg" xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape" xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"><sodipodi:namedview pagecolor="#303030" showgrid="true"><inkscape:grid id="grid5" units="px" spacingx="100" spacingy="100" color="#4772b3" opacity="0.2" visible="true" /></sodipodi:namedview><g fill="#fff"><path d="m307.48242 226.75c-.15739.006-.30286.0854-.39258.21484l-4 5.75c-.0583.0837-.0897.18317-.0898.28516v.5c.00003.27613.22387.49997.5.5h8c.27999.00002.50544-.22983.5-.50977l-.01-.47461c-.002-.0985-.0321-.19425-.0879-.27539l-3.99023-5.77539c-.0971-.14016-.25903-.22114-.42945-.21484z" transform="matrix(100 0 0 95.810448 -30200.009 -21618.174)"/></g></svg>
+<svg height="1600" viewBox="0 0 1100 1600" width="1100" xmlns="http://www.w3.org/2000/svg" xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape" xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"><sodipodi:namedview pagecolor="#303030" showgrid="true"><inkscape:grid id="grid5" units="px" spacingx="100" spacingy="100" color="#4772b3" opacity="0.2" visible="true" /></sodipodi:namedview><g fill="#fff"><path d="m264.49219 220.9707a.50005.50005 0 0 0 -.4336.29688l-4 9a.50005.50005 0 0 0 .10352.55664l4 4a.50005.50005 0 0 0 .70703 0l4-4a.50005.50005 0 0 0 .10352-.55664l-4-9a.50005.50005 0 0 0 -.48047-.29688zm.0234 1.73047 3.4043 7.65821-3.4043 3.40429-3.40429-3.40429z" fill-rule="evenodd" transform="matrix(100 0 0 100 -25901.562 -21997.038)"/></g></svg>

release/datafiles/icons_svg/pmarker_sel.svg

@@ -1 +1 @@
-<svg height="1600" viewBox="0 0 1100 1600" width="1100" xmlns="http://www.w3.org/2000/svg" xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape" xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"><sodipodi:namedview pagecolor="#303030" showgrid="true"><inkscape:grid id="grid5" units="px" spacingx="100" spacingy="100" color="#4772b3" opacity="0.2" visible="true" /></sodipodi:namedview><g fill="#fff"><path d="m264.49219 220.9707a.50005.50005 0 0 0 -.4336.29688l-4 9a.50005.50005 0 0 0 .10352.55664l4 4a.50005.50005 0 0 0 .70703 0l4-4a.50005.50005 0 0 0 .10352-.55664l-4-9a.50005.50005 0 0 0 -.48047-.29688zm.0234 1.73047 3.4043 7.65821-3.4043 3.40429-3.40429-3.40429z" fill-rule="evenodd" transform="matrix(100 0 0 100 -25901.562 -21997.038)"/></g></svg>
+<svg height="1600" viewBox="0 0 1100 1600" width="1100" xmlns="http://www.w3.org/2000/svg" xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape" xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"><sodipodi:namedview pagecolor="#303030" showgrid="true"><inkscape:grid id="grid5" units="px" spacingx="100" spacingy="100" color="#4772b3" opacity="0.2" visible="true" /></sodipodi:namedview><g fill="#fff"><path d="m243.49219 220.9707c-.18907.009-.3569.12383-.4336.29688l-4 9c-.084.18909-.0428.41038.10352.55664l4 4c.19526.19518.51177.19518.70703 0l4-4c.14634-.14626.1875-.36755.10352-.55664l-4-9c-.0836-.18859-.27441-.3065-.48047-.29688z" fill-rule="evenodd" transform="matrix(100 0 0 100 -23801.562 -21997.038)"/></g></svg>