Update logo and visual elements in Core to match new Jeedom brand identity

[Mips2648]

Jeedom updated its logo and visual identity (see the blog post: https://blog.jeedom.com/7739-evolution-du-logo-jeedom/).

It is necessary to plan the update of the logo and all related visual elements in the core, so that the application matches the new Jeedom brand identity.

Suggested tasks:

• Identify files/images to update (logo, favicon, splash, etc.)
• Adapt user interface elements as needed to conform to the new design