Don't render just spaces in a line

Motivation:

If a blank line is render, the text based renderer will include the
current indentation level resulting in lines with just spaces.

Modifications:

- Don't include indentation if the line to render is otherwise empty

Result:

Less trailing whitespace.

Author: glbrntt

Diff for: Sources/GRPCCodeGen/Internal/Renderer/TextBasedRenderer.swift

@@ -70,6 +70,9 @@ final class StringCodeWriter {
     if nextWriteAppendsToLastLine && !lines.isEmpty {
       let existingLine = lines.removeLast()
       newLine = existingLine + line
+    } else if line.isEmpty {
+      // Skip indentation to avoid trailing whitespace on blank lines.
+      newLine = line
     } else {
       let indentation = Array(repeating: " ", count: self.indentation * level).joined()
       newLine = indentation + line

Diff for: Tests/GRPCCodeGenTests/Internal/Translator/ServerCodeTranslatorSnippetBasedTests.swift

@@ -408,7 +408,7 @@ final class ServerCodeTranslatorSnippetBasedTests: XCTestCase {
               request: GRPCCore.StreamingServerRequest<NamespaceA_ServiceARequest>,
               context: GRPCCore.ServerContext
           ) async throws -> GRPCCore.StreamingServerResponse<NamespaceA_ServiceAResponse>
-          
+
           /// Documentation for outputStreamingMethod
           func outputStreaming(
               request: GRPCCore.StreamingServerRequest<NamespaceA_ServiceARequest>,
@@ -452,7 +452,7 @@ final class ServerCodeTranslatorSnippetBasedTests: XCTestCase {
               request: GRPCCore.StreamingServerRequest<NamespaceA_ServiceARequest>,
               context: GRPCCore.ServerContext
           ) async throws -> GRPCCore.ServerResponse<NamespaceA_ServiceAResponse>
-          
+
           /// Documentation for outputStreamingMethod
           func outputStreaming(
               request: GRPCCore.ServerRequest<NamespaceA_ServiceARequest>,
@@ -472,7 +472,7 @@ final class ServerCodeTranslatorSnippetBasedTests: XCTestCase {
               )
               return GRPCCore.StreamingServerResponse(single: response)
           }
-          
+
           internal func outputStreaming(
               request: GRPCCore.StreamingServerRequest<NamespaceA_ServiceARequest>,
               context: GRPCCore.ServerContext