Rename f8E4M3 to f8E4M3FN in mlir.extras.types py package (#97102)

Currently `f8E4M3` is mapped to `Float8E4M3FNType`.

This PR renames `f8E4M3` to `f8E4M3FN` to accurately reflect the actual
type.

This PR is needed to avoid names conflict in upcoming PR which will add
IEEE 754 `Float8E4M3Type`.
llvm/llvm-project#97118 Add f8E4M3 IEEE 754 type

Maksim, can you review this PR? makslevental ?

Author: apivovarov

mlir/python/mlir/extras/types.py

@@ -68,7 +68,7 @@ def ui(width):
 bf16 = lambda: BF16Type.get()
 
 f8E5M2 = lambda: Float8E5M2Type.get()
-f8E4M3 = lambda: Float8E4M3FNType.get()
+f8E4M3FN = lambda: Float8E4M3FNType.get()
 f8E4M3B11FNUZ = lambda: Float8E4M3B11FNUZType.get()
 
 none = lambda: NoneType.get()