Validate "-jvm-target" value in CLI, improve message

compiler/testData/cli/jvm/help.out

@@ -9,7 +9,7 @@ where possible options include:
   -script                    Evaluate the script file
   -kotlin-home <path>        Path to Kotlin compiler home directory, used for runtime libraries discovery
   -module-name               Module name
-  -jvm-target <1.6|1.8>      Compile code to specified JVM target: 1.6 or 1.8. Default one is 1.6.
+  -jvm-target <version>      Target version of the generated JVM bytecode (1.6 or 1.8), default is 1.6
   -language-version <version> Provide source compatibility with specified language version
   -nowarn                    Generate no warnings
   -verbose                   Enable verbose logging output

compiler/testData/cli/jvm/wrongArgument.out

@@ -10,7 +10,7 @@ where possible options include:
   -script                    Evaluate the script file
   -kotlin-home <path>        Path to Kotlin compiler home directory, used for runtime libraries discovery
   -module-name               Module name
-  -jvm-target <1.6|1.8>      Compile code to specified JVM target: 1.6 or 1.8. Default one is 1.6.
+  -jvm-target <version>      Target version of the generated JVM bytecode (1.6 or 1.8), default is 1.6
   -language-version <version> Provide source compatibility with specified language version
   -nowarn                    Generate no warnings
   -verbose                   Enable verbose logging output

compiler/testData/cli/jvm/wrongJvmTargetVersion.args

@@ -0,0 +1,5 @@
+$TESTDATA_DIR$/simple.kt
+-d
+$TEMP_DIR$
+-jvm-target
+1.5

compiler/testData/cli/jvm/wrongJvmTargetVersion.out

@@ -0,0 +1,3 @@
+error: unknown JVM target version: 1.5
+Supported versions: 1.6, 1.8
+COMPILATION_ERROR