Better indent in multi-line strings (KT-17849)

Inspired by MultilineStringEnterHandler from https://github.com/JetBrains/intellij-scala
https://github.com/JetBrains/intellij-scala/blob/edb741f344afff063197b406ca0c7c266a26c436/src/org/jetbrains/plugins/scala/editor/enterHandler/MultilineStringEnterHandler.scala

 #KT-17849 Fixed

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/dontInsertTrimMarginCall.kt

@@ -0,0 +1,5 @@
+val a = """blah blah<caret>""".trimMargin()
+//-----
+val a = """blah blah
+	|<caret>
+""".trimMargin()

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterInMethodCallMargin.kt

@@ -0,0 +1,5 @@
+val a = """blah blah<caret>""".replace("\r", "")
+//-----
+val a = """blah blah
+	|<caret>
+""".trimMargin().replace("\r", "")

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterInsideBraces.kt

@@ -0,0 +1,11 @@
+val a =
+	"""
+	  |  blah blah {<caret>}
+	""".trimMargin()
+//-----
+val a =
+	"""
+	  |  blah blah {
+	  |  <caret>
+	  |  }
+	""".trimMargin()

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterInsideText.kt

@@ -0,0 +1,8 @@
+object A {
+	val a = """blah<caret> blah"""
+}
+//-----
+object A {
+	val a = """blah
+		| <caret>blah""".trimMargin()
+}

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterMLSimpleMargin.kt

@@ -0,0 +1,14 @@
+val a =
+	"""
+	  | blah blah blah
+	  |  blah blah blah
+	  |    blah blah blah<caret>
+	"""
+//-----
+val a =
+	"""
+	  | blah blah blah
+	  |  blah blah blah
+	  |    blah blah blah
+	  |    <caret>
+	"""

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterMLStartOnSameLineMargin.kt

@@ -0,0 +1,8 @@
+val a = """blah blah blah
+		  |  blah blah<caret>
+		"""
+//-----
+val a = """blah blah blah
+		  |  blah blah
+		  |  <caret>
+		"""

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterOnNewLineMargin.kt

@@ -0,0 +1,7 @@
+val a =
+	"""<caret>"""
+//-----
+val a =
+	"""
+		<caret>
+	""".trimIndent()

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterSimpleMargin.kt

@@ -0,0 +1,9 @@
+class A {
+	val a = """<caret>"""
+}
+//-----
+class A {
+	val a = """
+		<caret>
+	""".trimIndent()
+}

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterWithTabsAfterMarginChar.kt

@@ -0,0 +1,16 @@
+fun some() {
+	val b = """
+		|class Test() {
+		|	fun test() {<caret>
+		|}
+		""".trimMargin()
+}
+//-----
+fun some() {
+	val b = """
+		|class Test() {
+		|	fun test() {
+		|	<caret>
+		|}
+		""".trimMargin()
+}

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterWithTextMargin.kt

@@ -0,0 +1,5 @@
+val a = """blah blah<caret>"""
+//-----
+val a = """blah blah
+	|<caret>
+""".trimMargin()

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/enterWithTextOnNewLineMargin.kt

@@ -0,0 +1,7 @@
+val a =
+	"""blah blah<caret>"""
+//-----
+val a =
+	"""blah blah
+		|<caret>
+	""".trimMargin()

idea/testData/editor/enterHandler/multilineString/withTabs/tabs4/settings.txt

@@ -0,0 +1,3 @@
+// SET_TRUE: USE_TAB_CHARACTER
+// SET_INT: TAB_SIZE=4
+// SET_INT: INDENT_SIZE=4