feat: allow independent management accounts with courses

[fntneves]

Expected Behavior

A single Swap instance should allow multiple management accounts and different academic "studies". "Studies" is a collection of courses under the same context. For instance, "Mestrado em Engenharia Informática" and "Mestrado Integrado em Ciências da Computação" have distinct courses.
Therefore, a management account would be allowed to create distinct fields of studies and have their own list of courses.

Current Behavior

Currently, a Swap instance only supports one administrator account and one set of courses.
That means that a new Swap instance is necessary if we want to apply to another context.

Possible Solution

It is possible to implement this by adding a new concept of "Studies". Within a "Studies" instance, there are multiple instances of Course concept that we already support. A management account should be able to create/modify/delete Studies and consequently their Courses.

[fntneves]

@djcouto Tell me your opinion about this.