Figure out HF types

[alastairong1]

We import hpos-hc-connect which contains Holofuel types, but we ignore them and redefine them here.

Furthermore, there are some inconsistencies in their definitions. For example in this repo Ledger struct fields are of type Fuel whereas in hpos-hc-connect they are of type string.

Copying a short conversation from PJ and Joel on the matter:

PJ:
Those are holofuel - specific types I think and because holofuel does not expose public crate with those types we are just manually defining them in the code of both hpos-api-rust and hpos_hc_connect. Shall we define them in one and import to another? I don't think so because they are holofuel specific and the only proper solution would be to make them available via holofuel types crate.

Joel:
I agree with this in general, but its a lot of work to extract it from the transactor_integrity zome. (I wish it was easier, zippy has tried it too) Thats why we created it in hpos_hc_connect for now.

https://github.com/Holo-Host/holofuel/pull/178 was may attempt to extract it fro the transactor_integrity zome, but its not completed