Switch to a different BIP39 implementation

[notmandatory]

The tiny-bip39 dependency used in the all-keys feature depends on zeroize which appears to only support MSRV 1.51+

https://github.com/iqlusioninc/crates/

This is causing the following error in our CI workflow:

Downloaded zeroize v1.4.0
error: failed to parse manifest at `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/zeroize-1.4.0/Cargo.toml`

Caused by:
  feature `resolver` is required

  this Cargo does not support nightly features, but if you
  switch to nightly channel you can add
  `cargo-features = ["resolver"]` to enable this feature
Error: Process completed with exit code 101.

https://github.com/bitcoindevkit/bdk/runs/3101954688?check_suite_focus=true

[notmandatory]

Can we switch to https://github.com/rust-bitcoin/rust-bip39? it's MSRV is 1.29.

[afilini]

Can we switch to https://github.com/rust-bitcoin/rust-bip39? it's MSRV is 1.29.

Yeah I guess it makes sense, I'm gonna reopen this issue to keep track of that

[notmandatory]

I did a preliminary look at swapping tiny-bip39 with rust-bip39 and the one missing part right now is rust-bip39 doesn't currently implement seed generation from the phrase.

[notmandatory]

As commented in bip39.rs, another option is to write our own bip-39 implementation, ideally with no new dependencies.

[notmandatory]

I confirmed that using @LLFourn 's PR maciejhirsz/tiny-bip39#29 patched version of tiny-bip39 in bdk I'm able to remove the fix from #400 and build and test the all-keys feature with rust 1.46.0.
Oops, nevermind. still broken after removing Cargo.lock and doing a cargo clean.