refactor: centralize sourceUrl and id-dedup checks across case-studies/radar-reports validators - #1739

Changed pages include:

• index.html - view
• 404.html - view
• architectures/index.html - view
• blog/index.html - view
• community/index.html - view
• events/index.html - view
• resources/index.html - view
• search/index.html - view
• architectures/adobe/index.html - view
• architectures/allianz/index.html - view

There are more changes not included in the list