Generating wpkh script type descriptors with compile

[i5hi]

Describe the enhancement
Currently compile only supports wsh, sh and sh-wsh. we require support for wpkh script type as well.

Use case
Although wpkh descriptors are straightforward to create by hand, calculating the checksum requires additional work. Checksum is required if we want to export a bdk wallet to certain other wallets - for example bitcoin core. Bitcoin core in particular supports calculating a checksum given a descriptor but not all wallets do.

Additional context
Please let me know if this is already possible in bdk-cli; if not I will make a PR to add support for wpkh.