fix(migrations): CockroachDB compatibility & separate permission tables

[bouassaba]

• fix(migrations): some fields were missing
• fix(migrations): some fields had wrong data type
• fix(migrations): some unique indexes were missing
• fix(api): update Go code to always set create_time

[bouassaba]

I found some issues in the data model when testing, I will need to fix them and ask for review again.

[bouassaba]

We get the following error when running the migrations in CockroachDB:

error returned from database: unknown signature: current_timestamp() (returning <string>)

Here is the explanation of the why from ChatGPT:

The error “unknown signature: current_timestamp() (returning )” during migration with Sea ORM when using CockroachDB is likely due to the way current_timestamp() is being interpreted. CockroachDB has specific functions and expected return types for date and time operations which can cause compatibility issues if not used correctly.

In Sea ORM, you typically define default values for timestamp columns using functions like current_timestamp(). However, CockroachDB has distinct variants of current_timestamp() that return different types, such as timestamp or timestamptz (timestamp with time zone). If the function call is not recognized with the correct return type, it results in the mentioned error.