Consider adding widget library template

[j-g00da]

We should consider adding a template for widget crates.

This can include:

• no_std attribute
• alloc linking
• ratatui-core dependency
• ratatui dev-dependency for tests
• maybe also std feature flag and conditional std linking

[joshka]

Great idea. Some extra things to add to such a template

• github workflows
• dependabot config
• guidance on naming the library (e.g. tui-foo)
• demo example with VHS tape setup to create images (+instructions on how to publish the images to vhs / github rather than in the repo)
• Optional imports of ratatui-crossterm for UI based widgets
• readme should have next steps (announce on discord / forum / awesome-ratatui)
• probably other things ...