Add icons for common elixir extensions

[skbolton]

eex and heex are for elixirs templating languages
exs is for elixir scripts
ex is the common extension for files

[jarun]

Sorry, please patch locally.

[skbolton]

I can go about this route but I think its worth calling out that the codebase has references to icons that it doesn't inject. Should I PR something that removes a reference to an elixir icon?

nnn/src/icons-in-terminal.h

Line 3513 in f4116a5

# define MFIZZ_ELIXIR "\uedc4"

[jarun]

Those come from the standard headers and as long as you don't use them, they don't take up memory.
As soon as you use them you add 2 overheads for people who don't need them:

• memory
• time spent in comparing the extensions

[N-R-K]

This got added in #1437