RFR: JDK-8244966: Add .vscode to .hgignore

[Lemmond, Dan]

Hi,

This is my first review request so apologies for any missteps or inconsistencies.

JBS: https://bugs.openjdk.java.net/browse/JDK-8244966
Webrev: http://cr.openjdk.java.net/~phh/8244966/webrev.01/

Please review this change that adds the .vscode directory to .hgignore, similar to the .idea directory. This directory is generated by various Visual Studio Code plugins during development.

Testing:
Local testing done, verified that .vscode/ no longer shows up when running hg status.

Thanks,
Dan