[bug fix] Add `maybe_descriptor_wallet_name()` in repl mode

[rajarshimaitra]

Description

Because we didn't had maybe_descriptor_wallet_name() in repl, the following command would fail

$ ./target/debug/bdk-cli repl -d "wpkh([b8b575c2/84'/1'/0'/0]tprv8icWtRzy9CWgFxpGMLSdAeE4wWyz39XGc6SwykeTo13tYm14JkVVQAf7jz8WDDarCgNJrG3aEPJEqchDWeJdiaWpS3FwbLB9SzsN57V7qxB/*)"
thread 'main' panicked at 'We should always have a wallet name at this point', src/bdk_cli.rs:116:10
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Checklists

All Submissions:

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

[notmandatory]

I sneaked in a commit to also fix #78

[thunderbiscuit]

Thanks for this! Sorry I'm late to the party, but I use the repl most of the time and these are great fixes. 🔥