feat(contracts): Fix Attestation ID generation in examples

[satyajeetkolhapure]

What does this PR do?

It adds chain prefix in attestation id generation logic in the examples where it was missing.

Related ticket

Fixes #787

Type of change

• Chore
• Bug fix
• New feature
• Documentation update

Check list

• Unit tests for any smart contract change
• Contracts and functions are documented

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.03%. Comparing base (316d91f) to head (13a9f5a).
Report is 5 commits behind head on dev.

Additional details and impacted files

@@             Coverage Diff             @@
##              dev     #797       +/-   ##
===========================================
+ Coverage   46.64%   74.03%   +27.38%     
===========================================
  Files          18       49       +31     
  Lines         388      905      +517     
  Branches       57      180      +123     
===========================================
+ Hits          181      670      +489     
- Misses        205      232       +27     
- Partials        2        3        +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.