Repository: cqfn/diKTat (kotlin)

Issue:
FP for gradle scripts
## Describe the bug
```kotlin
// build.gradle.kts
version = "0.1.0-SNAPSHOT"

// settings.gradle.kts
rootProject.name = "save"
```
should be allowed, but diktat suggests to wrap them in `run`.

 - `HEADER_MISSING_IN_NON_SINGLE_CLASS_FILE` shouldn't trigger for gradle scripts (should for regular kts files)

## Environment information
* diktat version: 0.5.0

Pull request description:
### What's done:
- Added handler for new line in script
- Closes #834

Patch:
diff --git a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter3/files/IndentationRule.kt b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter3/files/IndentationRule.kt
index ff8b059edc..d036844784 100644
--- a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter3/files/IndentationRule.kt
+++ b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter3/files/IndentationRule.kt
@@ -8,10 +8,7 @@ import org.cqfn.diktat.common.config.rules.RulesConfig
 import org.cqfn.diktat.common.config.rules.getRuleConfig
 import org.cqfn.diktat.ruleset.constants.Warnings.WRONG_INDENTATION
 import org.cqfn.diktat.ruleset.rules.DiktatRule
-import org.cqfn.diktat.ruleset.utils.getAllChildrenWithType
-import org.cqfn.diktat.ruleset.utils.getAllLeafsWithSpecificType
-import org.cqfn.diktat.ruleset.utils.getFilePath
-import org.cqfn.diktat.ruleset.utils.indentBy
+import org.cqfn.diktat.ruleset.utils.*
 import org.cqfn.diktat.ruleset.utils.indentation.ArrowInWhenChecker
 import org.cqfn.diktat.ruleset.utils.indentation.AssignmentOperatorChecker
 import org.cqfn.diktat.ruleset.utils.indentation.ConditionalsAndLoopsWithoutBracesChecker
@@ -23,7 +20,6 @@ import org.cqfn.diktat.ruleset.utils.indentation.IndentationConfig
 import org.cqfn.diktat.ruleset.utils.indentation.KdocIndentationChecker
 import org.cqfn.diktat.ruleset.utils.indentation.SuperTypeListChecker
 import org.cqfn.diktat.ruleset.utils.indentation.ValueParameterListChecker
-import org.cqfn.diktat.ruleset.utils.leaveOnlyOneNewLine
 
 import com.pinterest.ktlint.core.ast.ElementType.CALL_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.DOT_QUALIFIED_EXPRESSION
@@ -72,6 +68,7 @@ import kotlin.math.abs
  * Additionally, a set of CustomIndentationChecker objects checks all WHITE_SPACE node if they are exceptions from general rules.
  * @see CustomIndentationChecker
  */
+@Suppress("LargeClass")
 class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
     "indentation",
     configRules,
@@ -136,7 +133,7 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
      */
     private fun checkNewlineAtEnd(node: ASTNode) {
         if (configuration.newlineAtEnd) {
-            val lastChild = node.lastChildNode
+            val lastChild = generateSequence(node) { it.lastChildNode }.last()
             val numBlankLinesAfter = lastChild.text.count { it == '\n' }
             if (lastChild.elementType != WHITE_SPACE || numBlankLinesAfter != 1) {
                 val warnText = if (lastChild.elementType != WHITE_SPACE || numBlankLinesAfter == 0) "no newline" else "too many blank lines"


Test patch:
diff --git a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleWarnTest.kt b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleWarnTest.kt
index d73159b3ca..2d1690d0c5 100644
--- a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleWarnTest.kt
+++ b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleWarnTest.kt
@@ -11,6 +11,7 @@ import generated.WarningNames
 import org.junit.jupiter.api.Tag
 import org.junit.jupiter.api.Test
 
+@Suppress("LargeClass")
 class IndentationRuleWarnTest : LintTestBase(::IndentationRule) {
     private val ruleId = "$DIKTAT_RULE_SET_ID:indentation"
     private val rulesConfigList = listOf(
@@ -631,5 +632,29 @@ class IndentationRuleWarnTest : LintTestBase(::IndentationRule) {
         )
     }
 
+    @Test
+    @Tag(WarningNames.WRONG_INDENTATION)
+    fun `check script`() {
+        lintMethod(
+            """
+                |val q = 1
+                |
+            """.trimMargin(),
+            fileName = "src/main/kotlin/org/cqfn/diktat/Example.kts"
+        )
+    }
+
+    @Test
+    @Tag(WarningNames.WRONG_INDENTATION)
+    fun `check gradle script`() {
+        lintMethod(
+            """
+                |projectName = "diKTat"
+                |
+            """.trimMargin(),
+            fileName = "src/main/kotlin/org/cqfn/diktat/build.gradle.kts"
+        )
+    }
+
     private fun warnText(expected: Int, actual: Int) = "${WRONG_INDENTATION.warnText()} expected $expected but was $actual"
 }