Add macros from Sophacles' extra widgets

[joshka]

The style related widgets (bold! etc.) are pretty nice:
https://github.com/sophacles/extra-widgets/blob/main/src/text_macros/mod.rs

suggested in an issue ratatui/ratatui#118

[kdheepak]

Currently this is already possible:

"hello world".bold()

Is having this additionally going to be valuable?

bold!("hello world")

[joshka]

Maybe (unsure), the difference is runtime via an imported trait vs compile time via expansion.