API - Store exemption status

- in the database we need to store if a company is exempt from filing in the Registrar's Transparency Register _and_ the reason they are exempt
- need to be able to retrieve when we get company information
- need to be able to create and update that information
- enum on the businesses table for exemption
- investigate if we need a new endpoint or can reuse legal-api for existing company info page change flow

A company is exempt from filing and maintaining transparency register information if it falls under one of the categories below:
**Public company:**
- Reporting issuer (or equivalent)
- Listed on stock exchange
**Company is wholly owned:**
- By one or more Indigenous Nations
- Subsidiary of a reporting issuer (or equivalent)
- Subsidiary of a corporation listed on a stock exchange
- Subsidiary of a special act corporation
**Company incorporated or wholly-owned by**
- A municipality
- A regional district
**Other companies**
- Insurance company
- Trust company
- Government corporation
- Company that operates an independent school
- Company that has resulted from the conversion of a corporation under Part6.1 of the School Act

Start with the businesses table and the legal-api flow used to retrieve, create, and update company information. Confirm whether the existing company information endpoint can support exemption status and reason, or whether a new endpoint is needed; done means the exemption data is stored and available through the relevant company information flow.

Written by the indexing model from the issue text.