[util] Introduce IndentingPrinter interface

This interface is more convenient to pass around so that it's easier
to replace different printer implementations.

analysis/analysis-api-fir/analysis-api-fir-generator/src/org/jetbrains/kotlin/analysis/api/fir/generator/ArgumentsConverterGenerator.kt

@@ -78,7 +78,7 @@ object ArgumentsConverterGenerator {
     private fun SmartPrinter.generateSingleConverter(type: KClass<*>, converter: HLParameterConversion) {
         println("private fun $CONVERT_ARGUMENT(argument: ${type.typeWithStars}, firSymbolBuilder: KtSymbolByFirBuilder): Any? {")
         withIndent {
-            println("return ${converter.convertExpression("argument", ConversionContext(getCurrentIndentInUnits(), getIndentUnit()))}")
+            println("return ${converter.convertExpression("argument", ConversionContext(currentIndentLengthInUnits, indentUnitLength))}")
         }
         println("}")
         println()

analysis/analysis-api-fir/analysis-api-fir-generator/src/org/jetbrains/kotlin/analysis/api/fir/generator/rendererrs/FirDiagnosticToKtDiagnosticConverterRenderer.kt

@@ -59,7 +59,7 @@ object FirDiagnosticToKtDiagnosticConverterRenderer : AbstractDiagnosticsDataCla
     private fun SmartPrinter.printParameter(parameter: HLDiagnosticParameter) {
         val expression = parameter.conversion.convertExpression(
             "firDiagnostic.${parameter.originalParameterName}",
-            ConversionContext(getCurrentIndentInUnits(), getIndentUnit())
+            ConversionContext(currentIndentLengthInUnits, indentUnitLength)
         )
         println("$expression,")
     }