Create middleware to check if email is already in use for account changes.

[printharsh]

Tickets:

• HCK-185

List of changes:

Added middleware to check if email is already taken on changing email for accounts.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How has this been tested?

Manually changed email.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have made corresponding changes to the documentation
• Any dependent changes have been merged and published in downstream modules

[loreina]

is this a jank fix 👀

[pierreTklein]

This is the way I would do it:
have a middleware that does a query on hacker schema with given email. If it returns a hacker, and that hacker is not the hacker we are modifying, then do next({status: 409, ...}). We might even have this validation for account creation!