Feat/apikey dashboard

[thanhdatle]

Problem

Implement API Dashboard for user to generate APIKey, which is used to authenticate external APIs.

Solution

A new API endpoint is introduced:

api/user/hasApiKey

which returns either:

{"message":"true"} or {"message":"false"}

to indicate if user already has an API Key

If user has not generated API Key:

If user has generated API Key:

ApiKey modal is only shown once for user to copy API Key

The navigation header is also updated to add Dashboard and API Integration page

[halfwhole]

LGTM! Have put down a whole bunch of comments, but they're really nits that mostly have to do with minor frontend styling - works good without them!