Resolves #447

Add walkthrough drawer to guide initial configuration steps

• Replace walkthrough.md files with drawer based walkthrough in webview. Add short/long description to ensure nothing is lost from moving from markdown files.
• Update Patternfly version / icon version to fix version mismatch causing icon alignment issues.
• Parse 'settingsYaml' path (Provider config yaml settings file) for api key status & default config usage status. Listen for changes in this provider config to update walkthrough drawer as we do for the settings.json config changes.

TODO in follow up PR:
#477