feat(/convert): add support for short unit aliases

[kyranet]

Currently, /convert supports specifically 1 word for each unit, however, it doesn't support more forms (aliases), many of which can be auto-generated (e.g. sq m and sqm alias m², similarly, cb m and cbm for m³).

Similarly, supporting m2 and m3 as m² and m³ respectively would further improve the user experience.

Important

Not all languages support a custom prefix!. For example, in Spanish (Spain and LATAM) there is no equivalent to sq m (square meter) in a short form, only as a long form (metro cuadrado).