FND-382 - Add an isClassifiedBy restriction on Occurrence

[ElisaKendall]

Description

Added a restriction stating that an occurrence is classified by an occurrence kind, as requested by the Retail Domain Task force at OMG but also as needed for more sophisticated queries related to events in FIBO, such as those related to corporate actions, and cash flow analysis.

Fixes: #2001 / FND-382

Checklist:

• [x] I'm familiar with the FIBO developer quide. My contribution meets all the requirements described there.
• [x] My contribution follows the principles of best practices for FIBO.
• [x] My changes have been reconciled with latest master and no merge conflicts remain.
• [x] This PR is related to exactly one issue. The issue is referenced by using a GitHub keyword such as "fixes", "closes", or "resolves".
• [x] Hygiene tests have been applied by a PR with "(WIP)" in title.
• [x] The issue has been tested locally using a reasoner (for ontology changes).