feat(medusa): Convert SwapService to TypeScript (#2000)

**What**
- refactor swap service to typescript
- reimplement legacy methods
- use enums instead of magic strings

RESOLVES CORE-396

Co-authored-by: Oliver Windall Juhl <59018053+olivermrbl@users.noreply.github.com>

integration-tests/plugins/__tests__/medusa-plugin-sendgrid/index.js

@@ -178,7 +178,6 @@ describe("medusa-plugin-sendgrid", () => {
       order: {
         display_id: expect.any(Number),
         id: expect.any(String),
-        display_id: expect.any(Number),
         created_at: expect.any(Date),
         updated_at: expect.any(Date),
         customer_id: expect.any(String),