SEC-73 - Augment the equities concepts with their CFI classification

[ElisaKendall]

Signed-off-by: Elisa Kendall ekendall@thematix.com

Description

Added the concept of an extendable preferred share to equity instruments and updated the definition of limited partnership unit per the CFI standard.

Fixes: #1929 / SEC-73

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).