RFR: 8248843: java in source-file mode suggests javac-only options

[Adam Sotona]

`java` in source-file mode (see JEP 330) displays compiler notes suggesting `recompile with -Xdiags:verbose to get full output`. According JEP 330 these advanced `javac` optionns are not allowed. The goal with JEP 330 was to support developers that are at the early stages of learning Java, so options such as `-Xdiags:verbose` are out of their scope.

This patch prevents displaying `Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output` suggestion in `java` source-file mode by implicitly enabling `-Xdiags:verbose` in com.sun.tool.javac.launcher.Main for all invocations.

Beside avoiding prohibited `javac` option suggestion notes this patch has positive effect of more verbose compilation diagnostic. Higher diagnostic verbosity is appreciated by users learning Java on single-source programs in `java` source-file mode.

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Commit messages:
 - 8248843: java in source-file mode suggests javac-only options

Changes: https://git.openjdk.java.net/jdk/pull/4094/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4094&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8248843
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4094.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4094/head:pull/4094

PR: https://git.openjdk.java.net/jdk/pull/4094