Maintenance updates

[EPinci]

• Updated all base dependencies by resetting to a current starter extension template
  • Grabbed a current extension starter template (note the new dependencies and devDependencies)
  • Copied over the /src folder
• Updated code dependencies to latest available versions
• Consistently applied linting (now working without extensions) fixes thru the code
  • Exception for "Require statement not part of import statement @typescript-eslint/no-var-requires" that I couldn't find a way to fix
• Consistently removed deprecated calls thru the code
• Removed test stubs since there are no tests (test stubs are not anymore in the starter extension template)

Note that the @vscode/vsce dependency is now supposed to be installed globally to provide the vsce binary