test: improve createProof test coverage

[tplooker]

Description

Improves test coverage over the createProof API, this PR also improves the module loading logic when in NodeJS environments, so the CJS module can be consumed in non-NodeJS environments.

• [x] Tests for the changes have been added (for bug fixes / features)
• [x] The commit message(s) follow conventional commits
• [x] Documentation has been added / updated (for bug fixes / features)
• [x] Changes follow the contributing document.

Motivation and Context

See above

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Which merge strategy will you use?

• [x] Squash
• [ ] Rebase (REVIEW COMMITS)