Bugfix ga4 custom events

[paluchas]

Use correct gtag syntax to send (missing send_to) custom events.

• ga_events.js: add support for Google Analytics 4 property ID to track file downloads and metadata events
• saved.html.erb: add hidden input field for GA4 property ID to be used in ga_events.js script - Download button on save survey
• pdf.html.erb: add hidden input field for GA4 property ID to be used in ga_events.js script - Download button no survey

Add error from download survey save to Rails logger.

[paluchas]

On test I can see event-lable value for Downloaded and Metadata custom event. See screenshots

Navigate -> OASIS TEST GA4 -> Engagement -> Events

Select event name Downloaded. On updated report page select _Parameter name = pagetitle

Select event name Metadata. On updated report page select _Parameter name = eventlabel to see values of Journal titles.