Add methods to Descriptor + DescriptorPublicKey

[reez]

Description

https://docs.rs/bdk_wallet/latest/bdk_wallet/descriptor/enum.DescriptorPublicKey.html#method.master_fingerprint

https://docs.rs/bdk_wallet/latest/bdk_wallet/descriptor/enum.DescriptorPublicKey.html#method.is_multipath

https://docs.rs/bdk_wallet/latest/bdk_wallet/descriptor/enum.Descriptor.html#method.is_multipath

https://docs.rs/bdk_wallet/latest/bdk_wallet/descriptor/enum.Descriptor.html#method.into_single_descriptors

Would love for this to get into our beta6

Notes to the reviewers

Use Cases:

• creating a wallet from a descriptor having the ability to check if it's multipath or not
• creating a wallet from an xpub having the ability to construct a DescriptorPublicKey fromString then get the fingerprint

Changelog notice

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[rustaceanrob]

Concept ACK

Cool additions

[rustaceanrob]

Just out of curiosity, why are all of these access modifiers crate level? Clearly has no effect on the bindings but seems like a scope definition that doesn't actually apply

[reez]

good question/point-

[reez]

Concept ACK

Cool additions

Thanks!

[reez]

I get a failure because cargo clippy doesn't like the naming convention, I think the best option to get this to pass are renaming:

    pub(crate) fn to_single_descriptors(&self) -> Result<Vec<Arc<Descriptor>>, MiniscriptError> {
    }

will do that right now just cuz I would like this to pass even though that naming isn't exactly equivalent to the function we are wrapping.

[thunderbiscuit]

Just a tiny comment on the identation of the docstrings, but otherwise this is good to go IMO.

[reez]

Just a tiny comment on the identation of the docstrings, but otherwise this is good to go IMO.

Updated docstrings indentation, rebased, ready to merge 👍

[thunderbiscuit]

Sorry man I merged #629 before this one, so you'll have to rebase, but feel free to merge afterwards!