Add encoding configuration to logs

[rjmholt]

Not sure if we already do this or if it's possible, but we've had a few issues to do with encoding.

Ideally that information should just be in the logs.

Specifically we should add:

• The "files.encoding" to the VSCode extension logs
• PowerShell's $OutputEncoding (and possibly others) to the EditorServices logs

Thoughts? Any other suggestions?

[rjmholt]

Also add the full version (+ prerelease suffix) in the log file (PowerShell/PowerShellEditorServices#770).

[rjmholt]

It looks like getting VSCode's file encoding configuration may not currently be possible: microsoft/vscode#824

[rjmholt]

Unassigning myself since I've done all the work I think that can be done on this for the moment.

Leaving the issue open to track adding in VSCode's encoding configuration.