Keep imports closer to source in TypedExpressionEncoder

Revert the opinionated merge of the standalone `import ...Encoder` into a
braced group; add FramelessInternals as a separate plain import instead.
scalafmt does not merge imports, so this stays linter-clean while staying
closer to the original source.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: imarios

dataset/src/main/scala/frameless/TypedExpressionEncoder.scala

@@ -1,6 +1,7 @@
 package frameless
 
-import org.apache.spark.sql.{ Encoder, FramelessInternals }
+import org.apache.spark.sql.Encoder
+import org.apache.spark.sql.FramelessInternals
 import org.apache.spark.sql.catalyst.analysis.GetColumnByOrdinal
 import org.apache.spark.sql.catalyst.expressions.{
   BoundReference,