Separate JVM target option from javac's --enable-preview analogue

compiler/testData/cli/jvm/extraHelp.out

@@ -22,6 +22,8 @@ where advanced options include:
   -Xir-do-not-clear-binding-context
                              When using the IR backend, do not clear BindingContext between psi2ir and lowerings
   -Xemit-jvm-type-annotations Emit JVM type annotations in bytecode
+  -Xjvm-enable-preview       Allow using features from Java language that are in preview phase.
+                             Works as `--enable-preview` in Java. All class files are marked as preview-generated thus it won't be possible to use them in release environment
   -Xfriend-paths=<path>      Paths to output directories for friend modules (whose internals should be visible)
   -Xmultifile-parts-inherit  Compile multifile classes as a hierarchy of parts and facade
   -Xir-check-local-names     Check that names of local classes and anonymous objects are the same in the IR backend as in the old backend

compiler/testData/cli/jvm/jvmRecordOk.args

@@ -8,5 +8,6 @@ $TEMP_DIR$
 -jdk-home
 $JDK_15$
 -XXLanguage:+JvmRecordSupport
+-Xjvm-enable-preview
 -jvm-target
-15_PREVIEW
+15

compiler/testData/cli/jvm/jvmRecordOk.out

@@ -7,4 +7,6 @@ This mode is not recommended for production use,
 as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!
 
+warning: language version 1.5 is experimental, there are no backwards compatibility guarantees for new language and library features
+info: using preview Java language features
 OK

compiler/testData/cli/jvm/wrongJvmTargetVersion.out

@@ -1,3 +1,3 @@
 error: unknown JVM target version: 1.5
-Supported versions: 1.6, 1.8, 9, 10, 11, 12, 13, 14, 15, 15_PREVIEW
+Supported versions: 1.6, 1.8, 9, 10, 11, 12, 13, 14, 15
 COMPILATION_ERROR