Issue/768/support markdown emoji

[andrewpollack]

Thank you again for the advice on the previous PR! This is helping me learn better Rust coding practices, and I very much appreciate it 😄

This Pull Request fixes/closes #768.

It changes the following:

• Adds gh-emoji crate to dependencies.
• Updated changelog with png of change in action.
• Added new fn emojifi_string(s: &str) -> String to utils/mod.rs.
• Utilized above function to emojify messages in LogEntry.

I followed the checklist:

• [:heavy_check_mark: ] I added unittests
• [:heavy_check_mark: ] I ran make check without errors
• [:heavy_check_mark: ] I tested the overall application
• [:heavy_check_mark: ] I added an appropriate item to the changelog

[andrewpollack]

My local cargo fmt -- --check fails on this line here https://github.com/extrawurst/gitui/blob/779a811b58a756f0dfcd8358d9a6025219142f77/asyncgit/src/sync/tags.rs#L45 , but when I make the suggested changes, they fail for the linting that's run in the CI/CD here. Any thoughts on what I should do here?

[extrawurst]

@andrewpollack thanks for your contribution. Checkout d72dcdd To see what I improved