FND-379 - Need to add a definition for EBITDA

[ElisaKendall]

Description

Added a definition for earnings before interest, taxes, depreciation and amortization (EBITDA) to Accounting Equity in FND

Fixes: #1942 / FND-379

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).