Add SyncPortfolio and GetPortfolio endpoints

[jakobphilippe]

Description

Adds /etrade/sync/:user_id and /etrade/portfolio/:user_id

The sync endpoint retrieves and adds all the current positions in all of the user's etrade accounts to our db and returns the list of positions. The get portfolio endpoint simply returns the list of current positions from our db.

How Has This Been Tested?

Tested manually by calling the /etrade/sync/:user_id endpoint in both sandbox and prod environments.

Change below here. If this is a frontend MR, include screenshots

Add here

Checklist

• [x] I have performed a self-review of my code
• [ ] I have reached out to another developer to review my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] New and existing unit tests pass locally with my changes

[leoRysing]

Once the summary sync is done, this pr is good too merge 👍