feat: add fullform to output object mode

[carlos22]

A good UI uses <abbr> for the units with the full name as title. This is very hard to to with this lib. One would need to call it twice to the both, the short and long version of the symbol. In the output: 'object' mode it should be easy to add a unit prop with the fullform of the symbol?!

[avoidwork]

I'll add unit but it'll be the shortform, because symbol behavior can't change; it also works better for looking up the different specs imo.