Check cheatsheet is up to date in CI

[jesseduffield]

Is your feature request related to a problem? Please describe.
In lazygit we have a cheatsheet check script which tells us whether the cheatsheet we currently have is in line with what would be generated by the cheatsheet generation script.

We want to port this over to lazydocker and also run it on CI (see the lazygit approach for comparison)

This will ensure that nobody accidentally makes a change while forgetting to update the cheatsheet

[gusandrioli]

I can take this one as well :)

[jesseduffield]

Go right ahead @gusandrioli :)