* chore: make 'DirectSecp256k1HdWallet' only derive its keys once on construction
Previously all the keys and account information was being derived for every transaction signed
* no longer keep account seed on the wallet struct
* renamed secp265k1 to secp256k1
* added optional 'explicit_signer_data' argument for sign method
* wip
* made client signer generic
which required to undertake an adventure into coconut bandwidth trait bounds...
* separate wrapper for TxSigner
* moves signing-related features to separate module
* fixed build of binaries from outside default workspace
* offline signing example
* fixed wallet build
* post rebasing formatting
* fixed bity integration build
* making clippy happier
* fixed post-rebase bip39 dependency version
Jędrzej Stuczyński