clear and restore problematic NODE environment variables before calling orca

[jonmmease]

plotly.py already clears the NODE_OPTIONS environment variable before calling orca because it causes and electron segfault in the version of electron that orca currently relies on (See plotly/orca#124 and #1140). In plotly/orca#149 we discovered that the ELECTRON_RUN_AS_NODE environment variable that is set by VSCode also causes a problem.

We should at least clear the ELECTRON_RUN_AS_NODE variable before calling orca, but we should also investigate whether it is possible to restore both of these environment variables immediately after the orca call.

This should be fine when we're simply calling orca --help/orca --version because the orca process exits right away. But we'll have to be careful to test orca serve call, since this launches a long running server process. We'll need to make sure that restoring these environment variables after launching the server process doesn't cause the running process any issues.