Migrate from `zsh-expand` to `zsh-abbr` as it seems more performant and
isn't giving me unwanted expansions, such as when typing `run` within
this repository and it completing to something else.
Whilst Home Manager does have `programs.zsh-attr`, there isn't an option
for setting global abbreviations that expand anywhere in the command,
which I need to replace global ZSH aliases such as `G` which expands to
`| grep`.
For now, I've installed `zsh-abbr` via zplug and am creating the
`user-abbreviations` file using Home Manager where I can use `attr -g`
for global aliases.
If or when support is added for global abbreviations in Home Manager,
I'll switch to `programs.zsh-abbr.abbreviations`.
`programs.zsh.shellAliases` is still used for aliases that shouldn't
expand, whereas everything else has been moved to abbreviations.