feat: port Algebra.Lie.Weights (#4988)

Co-authored-by: Parcly Taxel <reddeloostw@gmail.com>

Author: xroblot

Mathlib.lean

@@ -236,6 +236,7 @@ import Mathlib.Algebra.Lie.Subalgebra
 import Mathlib.Algebra.Lie.Submodule
 import Mathlib.Algebra.Lie.TensorProduct
 import Mathlib.Algebra.Lie.UniversalEnveloping
+import Mathlib.Algebra.Lie.Weights
 import Mathlib.Algebra.LinearRecurrence
 import Mathlib.Algebra.ModEq
 import Mathlib.Algebra.Module.Algebra