Force the use of IL for SRG SSR content

[amtins]

Description

As a Pillarbox developer, I want SRG SSR content to be provided only by IL. To avoid promoting bad practice within SRG SSR.

Aceptance criteria

• Remove the options for overloading the IL url, the data transformation function and the mediaData property.
• Add the same behavior as Pillarbox Apple which providing an "enum" to be able to select the environment (test, stage, prod)
• Expose the SRGAnalytics class so that developers can easily create their own middleware.

[defagos]

We should check there is no documentation endorsing such practices but the code cannot really be removed. On mobile platforms this loophole has been closed.