Generic TangentGroup TG from action-parameterized ProductLieGroup

[AlessandroFornasier]

Tangent Lie group TG = G ⋉ 𝔤 on top of the action-parameterized ProductLieGroup.

Stacked on #2494, will be rebased once #2494 is merged.

Adds the tangent group of a Lie group, TangentLieGroup<G>, built as a semidirect ProductLieGroup<G, g, AdjointAction<G>> where G acts on its own Lie algebra g by the adjoint action φ(g,ξ) = Ad_g·ξ.

Changes

• TangentLieGroup.h: AdjointAction<G> and the TangentLieGroup<G> alias. Element (g, ξ), group law (g₁,ξ₁)·(g₂,ξ₂) = (g₁g₂, ξ₁ + Ad_{g₁}ξ₂), dimension 2·dim(G).
• ProductLieGroup: static algebra adjoint adjointMap(ξ) for semidirect products. It recurses through the base group's adjointMap, so tangent groups of products work as expected.

Tests

• testTangentLieGroup: group axioms/concepts, Exp/Log round-trip and Jacobians, the left-Jacobian transport block, and the Ad/ad block structure, on TG(SO3), TG(SE3), TG(Gal3).
• testActionProductLieGroup: an SE(3) ⋉ ℝ⁴ example (defined inline in the test) reconstructing Gal(3), cross-checked against the native Gal3 compose/between/inverse/Exp/Log/Adjoint, retract/local, and the static algebra adjoint.

[AlessandroFornasier]

@dellaert @rohan-bansal