[CLI] Make -Xcompiler-plugin experimental and K2 only

compiler/testData/cli/jvm/plugins/firAllOpenPlugin_modern.args

@@ -1,4 +1,5 @@
 -d
 $TEMP_DIR$
+-Xuse-k2
 -Xcompiler-plugin=dist/kotlinc/lib/allopen-compiler-plugin.jar=annotation=foo.AllOpen
 $TESTDATA_DIR$/firAllOpenPlugin.kt

compiler/testData/cli/jvm/plugins/firAllOpenPlugin_modern.out

@@ -1 +1,5 @@
+warning: argument -Xcompiler-plugin is experimental
+warning: ATTENTION!
+ This build uses experimental K2 compiler:
+  -Xuse-k2
 OK

compiler/testData/cli/jvm/plugins/mixingModernAndLegacyArgs.args

@@ -1,6 +1,7 @@
 -d
 $TEMP_DIR$
 -Xcompiler-plugin=dist/kotlinc/lib/noarg-compiler-plugin.jar=annotation=foo.NoArg
+-Xuse-k2
 
 -Xplugin=dist/kotlinc/lib/allopen-compiler-plugin.jar
 -P

compiler/testData/cli/jvm/plugins/multipleOptionsForOnePlugin.args

@@ -1,4 +1,5 @@
 -d
 $TEMP_DIR$
+-Xuse-k2
 -Xcompiler-plugin=dist/kotlinc/lib/allopen-compiler-plugin.jar=annotation=foo.AllOpen1,annotation=foo.AllOpen2
 $TESTDATA_DIR$/multipleOptionsForOnePlugin.kt

compiler/testData/cli/jvm/plugins/multipleOptionsForOnePlugin.out

@@ -1 +1,5 @@
+warning: argument -Xcompiler-plugin is experimental
+warning: ATTENTION!
+ This build uses experimental K2 compiler:
+  -Xuse-k2
 OK

compiler/testData/cli/jvm/plugins/multiplePlugins.args

@@ -1,5 +1,6 @@
 -d
 $TEMP_DIR$
+-Xuse-k2
 -Xcompiler-plugin=dist/kotlinc/lib/allopen-compiler-plugin.jar=annotation=foo.AllOpen
 -Xcompiler-plugin=dist/kotlinc/lib/noarg-compiler-plugin.jar=annotation=foo.NoArg
 $TESTDATA_DIR$/multiplePlugins.kt

compiler/testData/cli/jvm/plugins/multiplePlugins.out

@@ -1,4 +1,7 @@
-compiler/testData/cli/jvm/plugins/multiplePlugins.kt:11:17: error: noarg constructor generation is not possible for inner classes
+warning: ATTENTION!
+ This build uses experimental K2 compiler:
+  -Xuse-k2
+compiler/testData/cli/jvm/plugins/multiplePlugins.kt:11:17: error:
     inner class Inner(val s: String)
                 ^
 COMPILATION_ERROR

compiler/testData/cli/jvm/plugins/multiplePluginsInSameArg.args

@@ -1,4 +1,5 @@
 -d
 $TEMP_DIR$
+-Xuse-k2
 -Xcompiler-plugin=dist/kotlinc/lib/allopen-compiler-plugin.jar,dist/kotlinc/lib/noarg-compiler-plugin.jar=annotation=foo.AllOpen
 $TESTDATA_DIR$/multiplePluginsInSameArg.kt

compiler/testData/cli/jvm/plugins/noPluginInClasspath.args

@@ -1,4 +1,5 @@
 -d
 $TEMP_DIR$
+-Xuse-k2
 -Xcompiler-plugin=dist/kotlinc/lib/kotlin-reflect.jar
 $TESTDATA_DIR$/noPluginInClasspath.kt

compiler/testData/cli/jvm/plugins/pluginSimple_modern.out

@@ -1 +0,0 @@
-OK

compiler/testData/cli/jvm/plugins/pluginSimple_modern_noK2.out

@@ -0,0 +1,2 @@
+error: -Xcompiler-plugin argument is allowed only for for K2 compiler. Please use -Xplugin argument or enable -Xuse-k2
+COMPILATION_ERROR