SEC-164 - Further revisions to the AssetBackedSecurities ontology are needed

[ElisaKendall]

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

Description

1. Cleaned up ABS with respect to bonds that were already defined in the bonds ontology
2. Added controlled amortization ABS
3. Added fully amortizing ABS
4. Moved bond pool from CDOs to ABS

Fixes: #1918 / SEC-164

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).