feat: port Analysis.NormedSpace.LinearIsometry (#3289)

Co-authored-by: Parcly Taxel <reddeloostw@gmail.com>
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

Author: 3 people

Mathlib.lean

@@ -373,6 +373,7 @@ import Mathlib.Analysis.NormedSpace.ContinuousLinearMap
 import Mathlib.Analysis.NormedSpace.Extr
 import Mathlib.Analysis.NormedSpace.IndicatorFunction
 import Mathlib.Analysis.NormedSpace.Int
+import Mathlib.Analysis.NormedSpace.LinearIsometry
 import Mathlib.Analysis.NormedSpace.MStructure
 import Mathlib.Analysis.NormedSpace.Pointwise
 import Mathlib.Analysis.NormedSpace.Ray