[FEAT] Provide a Connection/Secret provider/handler to define generic configuration for Activities (ConnetionString, Storage Account...)

## Feature Request

### Problem Overview / Use Cases
**Is your feature request related to a problem? Please describe.**

As a developer, I would like to define some sort of Connection or Secret in a central repository.
For example, a SQL Connection String or a couple of property that define general settings for a Activity.

For a database connection, we could have activity like Select, Insert etc... which can be defined in differents activity but rely on the ConnectionString Property to configure the SQLClient.

For a Cloud Storage Connection, (eg: S3), we have the following properties :
- accessKey
- secretAccessKey
- region

which can be group in a `Connection` concept that identify a configuration to a specific S3 repository

Then this `Connection` is used in the client for different activities :
- Upload File
- List Objects
etc...

In this case, If I want then to modify the S3 Storage Account, I can do it in one central place with no need to change the configuration in all the workflow that use this activity.

As a Operator, I want to be able to configure these connections in different environnement (Dev/UAT/Prod) and then just Export / Import Workflow without changing any configuration.

As an Administrator, I can be able to __CREATE__ `Connection configuration` and the developer of the workflow can __USE__ the connection but __NOT READ__ it

### Proposed Solution
**Describe the solution you'd like**

I would like to define something like a `ConnectionProperty` in the Activity.
Where `T` is the model representing the properties use for the configuration.

In the Workflow Definition, only the connection Name should be appears in the JSON because Sensitive information can be present in the configuration. We could for example :
- use new `[Attribute]` to define the `connection type`, `connection model`
- use a `IActivityExecutionMiddleware` before the `ActivityExecutionMiddleware` which can be able to :
- identify that activity has connection and get the `Type`
- get the `connection name`
- use a ConnectionStore to retrieve the `properties` regarding (`Type`, `ConnectionName`)
- Set the `T` model of the Activity

In the Log Persistence, I would like to be able to obfuscate some property of the `T` model (enforced in code, maybe not unlockable by the strategy , or with some debug flag (to be sure that no leak can be done on a production environment)
We could for example :
- define a `[NoLog]` attribute
- use a `ActivityStateFilterBase` to obfuscate some part of the `T` model

(The [Nolog] attribute could be more generic and the `StateFilter` can for eg: obfuscale just a part of a sql connection string.

then we need a UI to CRUD the connection regarding `activity Type` available in the `Registry`.

### Impact of Feature

Configuration centralization, easier continuous delivery and transport configuration between environment.

### Visuals and Mockups
**Provide any visuals**

Drop down to select connection, we can define a custom UI-hint and add a `ADD` button to be able to create and use a new connection directly from this screen

obfuscation :