Allow LaTeX to unicode completion to support consecutive sub/superscript characters

[tomchor]

I feel like this issue must have been opened in the past but I could't find it. So feel free to close it if it has.

Basically since Julia 1.6 we can type consecutive supercripts or subscripts characteres pretty easily (with just one tab):

help?> Aᵃᵇᶜᵈᵉᶠ
"Aᵃᵇᶜᵈᵉᶠ" can be typed by A\^abcdef<tab>

But it appears that julia-vim still doesn't have that capability, so to type the same variable name as above on Vim I'd have to type:

A\^a<tab>\^b<tab>\^c<tab>\^d<tab>\^e<tab>\^f<tab>

Is there any way to make the julia-vim behavior similar to that of the Julia REPL?