LOAN-168 - Revise the Loans ontologies as the basis for green loans (WIP)

[ElisaKendall]

Description

1. Split the MortgageLoans ontology into two separate ontologies - one small-ish ontology describing mortgages, but limited to primary contract details, with a second ontology including the origination and servicing content that was previously in MortgageLoans. Resulting ontologies include Mortages and MortgageOrigination (which may be split again into origination and servicing components)

Fixes: #2061 / LOAN-168

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).