Improved timeseries chart view

• Consistent support for dark/ light mode and accent color on timeseries chart view
• Added sub navigation on timeseries chart view for toggling legend and filtering related metric tags
• The journal view now opens immediately on application start if there are log entries
• Updated elementary OS Sdk to runtime version 6.1
• Replaced LiveChart.StaticChart with WebKit.WebView
• Updated Stripe key for integration with AppCenter