[v0.1.2] Support for Outline, improved Diagnostics, and Locale configuration setting

[mattmasson]

This change takes advantage of the improvements in the powerquery-language-services 0.1.11 release.

Adds support for the document Outline window

Diagnostics now include errors for duplicate identifiers

Added "powerquery.general.locale" configuration setting to control parser/diagnostic error message locale/culture.

{
  "powerquery.trace.server": "verbose",
  "powerquery.general.locale": "en-US"
}

Issues

• The locale setting only takes effect on the next launch of vscode - I couldn't figure out how to pick up config changes as they happen. Requires further investigation.
• Not all diagnostic messages are localized (needs to be resolved in powerquery-language-services)