Fix support for Eclipse Theia

[datho7561]

When try to use the extension in Theia, I get

Launching server using command /home/davthomp/Documents/Projects/theia/examples/browser/undefined/bin/java failed.

It would be nice to figure out why this is happening and address it.

[rgrunber]

An inspection of /home/davthomp/Documents/Projects/theia/examples/browser/undefined/bin/java may explain things.

[datho7561]

If I add:

// ...
  executable.command = path.resolve(requirements.tooling_jre ?? requirements.java_home + '/bin/java');
// ...

to prepareExecutable in javaServerStarter, then I can get the error to go away. (I think I'm just running a version of vscode-java without the JDK bundled). Even with this change, though, I still don't get lsp4mp features in properties files.

[datho7561]

Here are the steps to fix this issue:

• Make sure that you are running the most recent vscode-java (1.10.0 or 1.11.0); I think Theia installs 1.1.0 from openvsx by default
• Add the following setting to the JDT-LS vmargs: -Xlog:disable
• Add the following setting to the lsp4mp vmargs: -Xlog:disable

[datho7561]

By default, Theia installs vscode-java 1.1.0 from the marketplace. This is because it is the newest release of vscode-java that has a vscode engine version compatible with Theia. Unless the user manually installs the .vsix for vscode-java and vscode-microprofile, it won't work in Theia