Implement source sections compiler plugin

allows to compile only parts of the source files, denoted by top-level
"sections" (function with lambda param calls), but preserving original
file line/column numbers for easier diagnostics. Allow e.g. to compile
gradle "buildscript" section without preprocessing original file in
advance. See tests for examples.

plugins/source-sections/source-sections-compiler/testData/sourceSectionsBasics.kts

@@ -0,0 +1,22 @@
+
+println("should not be printed")
+
+fun unlistedSectionName(body: () -> Unit): Unit = body()
+
+let {
+   println("Hello, World!")
+}
+
+println("ignore here")
+
+unlistedSectionName {
+   println("should not be printed too")
+}
+
+println("ignore here")
+
+apply {
+   println("That's all, folks!")
+}
+
+println("ignore here")

plugins/source-sections/source-sections-compiler/testData/sourceSectionsBasics.kts.filtered

@@ -0,0 +1,22 @@
+
+
+
+
+
+let {
+   println("Hello, World!")
+}
+
+
+
+
+
+
+
+
+
+apply {
+   println("That's all, folks!")
+}
+
+

plugins/source-sections/source-sections-compiler/testData/sourceSectionsBasics.kts.out

@@ -0,0 +1,2 @@
+Hello, World!
+That's all, folks!