tests: add the NAFEMS LE7 cylinder/sphere oracle case

The thin-walled cylinder with a hemispherical cap under internal
pressure as four axisymmetric quad8 blocks: axial stress on the outer
surface at D 25.283.

The NAFEMS target, 25.86, is the axisymmetric thin-shell solution; our
solid model converges to 25.27, the value ESRD reports for its converged
axisymmetric solid. So the NAFEMS quantity keeps a 1% tolerance and is
a known failure until there is an axisymmetric shell element, and a
second quantity checks the model against the solid reference (pass,
0.05%).

Part of #97.

tests/oracle/nafems-le7/fixture.json

@@ -0,0 +1,9 @@
+{
+  "note": "FieldCraft's accepted results for this case, written by `cargo xtask oracle --bless`. A result outside its band fails CI.",
+  "values": {
+    "syy_D_solid": {
+      "band": 2.5282545696283336e-8,
+      "value": 25.282545696283336
+    }
+  }
+}