PublicKey and XOnlyPublicKey should not *derive* Debug

[Kixunil]

It should be manually implemented to show the key as serialized. Otherwise it shows just the internal data which, for the purpose of debugging, is just a garbage. See also: rust-bitcoin/rust-bitcoin#3278

[apoelstra]

For the purpose of debugging, is it garbage? I guess it depends on what level you are debugging at. If you are debugging this library then presumably you want the raw representation.

Weak concept ACK, but I can see either side on this one.

[Kixunil]

If you really need to debug the internal representation you should use the FFI type which appropriately shows the internal representation. (But calling it out in the doc would be nice.)