Transform: remove constraints from the redo panel

Constraint options had confusing behavior:

- When non were pressed, the orientation was ignored.
- When any were pressed, the orientation was used,
  but only unconstrained axed could be adjusted.

Now constraining is only used for modal execution
so there is no need to show these in the interface.

When an orientation is selected, the XYZ values always transform
using that space.

Note, transform system should be refactored to support different
orientations w/o having to use constraints.

Addresses T57204

source/blender/editors/transform/transform.h

@@ -764,7 +764,16 @@ enum {
 
 /* transinfo->con->mode */
 enum {
+	/**
+	 * TODO(campbell): this has two meanings:
+	 * - Constraint axes.
+	 * - Transform values are evaluated in different orientation.
+	 *
+	 * We should split out this second meaning into another flag
+	 * because transform logic becomes hard to follow when we're
+	 * only want to support an alternate orientation. */
 	CON_APPLY =       1 << 0,
+	/** These are only used for modal execution. */
 	CON_AXIS0 =       1 << 1,
 	CON_AXIS1 =       1 << 2,
 	CON_AXIS2 =       1 << 3,