MG-2236 - Add Constraints Service Provider

[WashingtonKK]

What type of PR is this?

This is a feature because it adds a constraint provider to magistrala.

What does this do?

This introduces a constraint provider to magistrala that reads constraints from a toml file and uses this to limit the entities created.

Which issue(s) does this PR fix/relate to?

• Resolves absmach/amdm#98

Have you included tests for your changes?

Yes, I have included tests for my changes.

Did you document any new/modified feature?

Yes, I have updated the documentation for the new feature.

Notes

[arvindh123]

|-- constraints
|   |-- config
|   |   |-- configprovider.go
|--constraints.go

@WashingtonKK What do you think about this folder structure, inside pkg dir But again it like similar to repo folder structure

[arvindh123]

|-- constraints
|   |-- config
|   |   |-- configprovider.go
|--constraints.go

@WashingtonKK What do you think about this folder structure, inside pkg dir But again it like similar to repo folder structure

In future we can add other providers

like example

|-- constraints
|   |-- config
|   |   |-- configprovider.go
|   |-- strip
|   |   |-- stripprovider.go
|--constraints.go

[WashingtonKK]

|-- constraints
|   |-- config
|   |   |-- configprovider.go
|--constraints.go

@WashingtonKK What do you think about this folder structure, inside pkg dir But again it like similar to repo folder structure

In future we can add other providers

like example

|-- constraints
|   |-- config
|   |   |-- configprovider.go
|   |-- strip
|   |   |-- stripprovider.go
|--constraints.go

@arvindh123 I think this is a good idea, since it will make it easy for us to add more providers. I will update it to that

[dborovcanin]

We will be using middlewares for this, to keep Service relatively independent. Also, some constraints may refer to certain types of limits that fit better to API (filtering by API key, advanced rate-limiting...).