feat(pack): add elixir lang pack with `expert` #9958

Job	Run time
CI / Selene Linting	5s
CI / Stylua Formatting	5s
CI / Conventional Commit Messages	0s
Announcement	0s
CI / Spell Check	0s
Calculate scopes	0s
CI / Release Please	0s
PR	0s
CI / Generate Vimdoc	0s
	10s

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