lib: add Amount, Network

[rustaceanrob]

Here I added Amount and Network. To convert to and from the UniFFI and internal types I added some macros, which may be moved into a marcos.rs or a more general utils.rs. I also added thiserror as we seemed to roughly agree it is appropriate as a dependency on the dev call.

[thunderbiscuit]

I have a few questions/comments but this looks really good!

[thunderbiscuit]

Great stuff! Took me a minute to parse it but I think this is an example of a macro that's simple and worth having. It also ensures we reduce the number of places where these simple workflows are written. I'm fine with those as is, but how do you feel about renaming the field like so:

macro_rules! impl_from_core_type {
    ($core_type:ident, $ffi_type:ident) => {
        impl From<$core_type> for $ffi_type {
            fn from(core_type: $core_type) -> Self {
                $ffi_type(core_type)
            }
        }
    };
}

?

[rustaceanrob]

Makes sense to me

[thunderbiscuit]

Same comment as above basically.

[thunderbiscuit]

I also think it's more intuitive to:

1. Reverse the order of the arguments
2. Name the macro impl_from_ffi_type()

So that the call site looks like this:

impl_from_ffi_type!(Amount, BitcoinAmount);

[rustaceanrob]

Do you think these make sense to move to a "macros.rs" or "utils.rs"

[thunderbiscuit]

Yeah I would have them in a macro.rs file.

[rustaceanrob]

Can't do macro singular cause that's a keyword. Went with macros, going to force push in a sec

[thunderbiscuit]

By the way I tested this locally with bitcoindevkit/bdk-ffi#546 and it works well. The import statements have to be adjusted for tests, and that's about it. Great stuff.

[rustaceanrob]

Pushed those updates up

[thunderbiscuit]

ACK eb01b76