Support for `rustic-mode`

[mcamou]

I am using Doom Emacs with rustic instead of rust-mode. evcxr-minor-mode is hardcoded to use e.g. rust-mode-map, which results in Symbol’s value as variable is void: rust-mode-map when trying to enable evcxr-minor-mode. Would it be possible to make evcxr-minor-mode compatible with rustic?