DER-138 - Need to add relationships to tranches and model them with respect to an index tranche CDS

[ElisaKendall]

Description

1. Augmented the CDS ontology to include credit default swap index and basket of credit default swaps as a starting point for adding attachement and detachment points and other analytics
2. Added concepts including collateral value as of date and 'has estimated total collateral value at issuance'
3. Added concepts related to attachment and detachment points

Fixes: #1973 / DER-138

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).