Update application design

[paper-lark]

First of all, thank you for this awesome app!
I've made some changes to the UI and I wondered if you would like to merge them. I did not make any changes to the logic of the app – only the looks. Below is a screenshot of the result.

[kdheepak]

Wow! Thanks for taking this on! I personally really like it (from the screenshot). It brings taskwarrior-tui more in line with the taskwarrior command line interface too. I also like that you cleaned up the code too :)

Let me get back to my computer and use it, and see if I have any other feedback. But, yes I'd be very happy to merge this!

[kdheepak]

It looks good to me. I might make more changes once I refactor the code too.

There's a bunch of formatting and clippy warnings. Would you like to deal with them or should I?

[paper-lark]

Thanks for the feedback! I will fix formatting a bit later.

[paper-lark]

Strangely, I did not see clippy warning from the latest build when running the same command locally. Anyhow, seems by now I should have fixed them all

[kdheepak]

Probably a new rust / clippy version? Thanks for making all the changes.

[kdheepak]

Light mode screenshot comparing old version and new version:

[kdheepak]

I've made a new release with this redesign: https://github.com/kdheepak/taskwarrior-tui/releases/tag/v0.21.0

Thanks for submitting the PR.