Implement blur effect for top header subsections

[JorgeDecentraland]

Some elements of the UI require an effect that blurs whatever elements they have behind.

[JuanSalice]

Planning for a restructuring of the UI is needed before advancing on implementation.

[sandrade-dcl]

After the meet we have had @JuanSalice, @lorux0 and me about how to integrate the bluf effect in our UI, we have reached the next conclusions:

1. Juan is going to create and configure an UI Camera that will be used for all our UI canvas.
2. We will need to create some kind of reference to the new UI Camera in order to be accessed from our code.
3. All the UI canvas in our client should be modified in order to change its Render Mode from Screen Space - Overlay to Screen Space - Camera. Once it is set to Screen Space - Camera, we will have to set the Render Camera with the UI Camera created in the step 1. This assignation will be done dinamically usaing the reference created in the step 2.
4. The same for the UI canvas used for the scenes.
5. We will have to take care about the Mouse Catcher game object because it wont let us click in the UIs with the new canvas configuration.
6. From this point on, for new UI prefabs that we need to create, we will use a non-canvas parent that will contain the needed canvases (as minimum one configured as Overlay and, depending on the needs, we could have another one configured as Camera). This parent game object will contain components like the Animator or the logic script related to the UI Component view.

[JuanSalice]

• Blur implementation is ready to be made, but some changes are needed in the main menu prefab

[MichaelBitsakis]

Applied BlurRT UI Image Element shader to AvatarEditorHUD --> Header