Summary

Fixes #1556

ginkgo outline did not recognize DescribeTableSubtree and its variants
(FDescribeTableSubtree, PDescribeTableSubtree, XDescribeTableSubtree),
causing the outline to miss the node entirely and flatten its children.

This PR:

• Adds all DescribeTableSubtree variants to the node recognition in ginkgoNodeFromCallExpr

• Adds expandSubtree logic to restructure the tree so each Entry under a
  DescribeTableSubtree gets a copy of the subtree's spec nodes as children,
  mirroring runtime behavior

• Adds a dedicated test fixture covering: single/multi-spec body, focused,
  pending, and X-pending variants

• Updates existing fixtures (focused, pending, nodot, alias) to include
  DescribeTableSubtree variants

Test plan

• go vet ./... passes
• ginkgo -r -p — all 17 suites pass, 0 failures
• New dedicated fixture: describe_table_subtree_test.go with CSV + JSON
• Updated fixtures: focused_test.go, pending_test.go, nodot_test.go, alias_test.go