Support imports in file compiler (#3921)

lang/jvm/src/main/scala/com/wavesplatform/lang/FileCompiler.scala

@@ -0,0 +1,33 @@
+package com.wavesplatform.lang
+
+import com.google.common.base.Charsets
+import com.google.common.io
+import com.wavesplatform.lang.v1.estimator.v3.ScriptEstimatorV3
+
+import java.io.File
+
+object FileCompiler extends App {
+  private val estimator = ScriptEstimatorV3.latest
+
+  args
+    .foreach { path =>
+      val scriptFile = new File(path).getAbsoluteFile
+      require(scriptFile.isFile, s"$path is not a file")
+      val baseDirectory = scriptFile.getParentFile
+      val imports = baseDirectory
+        .listFiles({ (pathname: File) =>
+          pathname.isFile && pathname.getAbsoluteFile != scriptFile
+        })
+        .map { f =>
+          f.getName -> io.Files.asCharSource(f, Charsets.UTF_8).read()
+        }
+        .toMap
+
+      API
+        .compile(io.Files.asCharSource(scriptFile, Charsets.UTF_8).read(), estimator, libraries = imports)
+        .fold(
+          error => throw new RuntimeException(s"$error while compiling $path"),
+          _ => println(s"successfully compiled $path")
+        )
+    }
+}