Better gnoland/home realm configuration for each network

[moul]

test4, test5, and portal (and maybe gnodev?) appear similar when you visit the homepage.

The current homepage seems tailored specifically for portal loop.

testX.gno.land should feature a distinctly different homepage that welcomes users to the testnet. It should explain its unique characteristics, provide suggestions on what to try, and include links for further information. Additionally, if users want to explore alternatives, there should be a link to portal loop.

gnodev should have something for local dev.

[leohhhn]

Related & awaiting your thoughts:

• [r/gnoland/home] Better CTA & content organization #3249

This is something I plan to implement in the rework of the home realm. I also want to add the ability to add/remove sections dynamically via transactions. We can definitely add sections that show up depending on the network:
if std.GetChainID() == "dev" {...}