RFR: 8329581: Java launcher no longer prints a stack trace

[Sonia Zaldana Calles]

Hi folks, 

This PR aims to fix [JDK-8329581](https://bugs.openjdk.org/browse/JDK-8329581). 

I think the regression got introduced in [JDK-8315458](https://bugs.openjdk.org/browse/JDK-8315458). 

In the issue linked above, [LauncherHelper#getMainType](https://github.com/openjdk/jdk/pull/16461/files#diff-108a3a3e3c2d108c8c7f19ea498f641413b7c9239ecd2975a6c27d904c2ba226) got removed to simplify launcher code.

Previously, we used ```getMainType``` to do the appropriate main method invocation in ```JavaMain```. However, we currently attempt to do all types of main method invocations at the same time [here](https://github.com/openjdk/jdk/blob/master/src/java.base/share/native/libjli/java.c#L623). 

Note how all of these invocations clear the exception reported with [CHECK_EXCEPTION_FAIL](https://github.com/openjdk/jdk/blob/140f56718bbbfc31bb0c39255c68568fad285a1f/src/java.base/share/native/libjli/java.c#L390). 

Therefore, if a legitimate exception comes up during one of these invocations, it does not get reported. 

I propose reintroducing ```LauncherHelper#getMainType``` but I'm looking forward to your suggestions. 

Cheers, 
Sonia

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Commit messages:
 - 8329581: Java launcher no longer prints a stack trace

Changes: https://git.openjdk.org/jdk/pull/18786/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18786&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329581
  Stats: 53 lines in 2 files changed: 45 ins; 2 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/18786.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18786/head:pull/18786

PR: https://git.openjdk.org/jdk/pull/18786