FBC-317 - The concepts related to interest rate schedules, rate resets and related events needs to be cleaned up

[ElisaKendall]

Description

1. Replaced the term 'swap stream' with 'swap leg' or 'leg' in some cases
2. Moved general concepts related to anchor dates, calculations and calculation periods to financial dates, to enable broader use
3. Moved concepts related to interest rate schedules and calculations to the debt ontology to normalize the pattern used across FIBO
4. Moved concepts related to step schedules to the debt instruments ontology and normalized their usage

Fixes: #1996 / FBC-317

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).