New generate mnemonic command

[remyroy]

What I did

Implements a new generate-mnemonic command to simply generate a new mnemonic to be displayed on screen or written to a file.

Related issue

Related to #283, #170

[valefar-on-discord]

Everything looks good from my end. I think this checks all the boxes that was asked.

Is this something we want to document or have it be a hidden command to not confuse with new-mnemonic?

[remyroy]

It would need to be documented and some unit tests would need to be added. I'm not sure what's the best way to avoid any confusion between this command and the existing new-mnemonic one. I'm thinking about a detailed description in the documentation and the stdout when you run this command could help.

[remyroy]

I've added documentation about this command to better explains this in relation with the existing new-mnemonic and the existing-mnemoniccommands including a small sentence after someone uses the new generate-mnemonic command.

[github-actions]

Test Coverage: Download HTML Report

Name                                                                 Stmts   Miss  Cover
----------------------------------------------------------------------------------------
ethstaker_deposit/__init__.py                                            1      0   100%
ethstaker_deposit/bls_to_execution_change_keystore.py                   32      2    94%
ethstaker_deposit/cli/__init__.py                                        0      0   100%
ethstaker_deposit/cli/existing_mnemonic.py                              45      0   100%
ethstaker_deposit/cli/exit_transaction_keystore.py                      44      3    93%
ethstaker_deposit/cli/exit_transaction_mnemonic.py                      67      9    87%
ethstaker_deposit/cli/generate_bls_to_execution_change.py               62     11    82%
ethstaker_deposit/cli/generate_bls_to_execution_change_keystore.py      45      3    93%
ethstaker_deposit/cli/generate_keys.py                                  66      2    97%
ethstaker_deposit/cli/generate_mnemonic.py                              43     16    63%
ethstaker_deposit/cli/new_mnemonic.py                                   33      0   100%
ethstaker_deposit/cli/partial_deposit.py                                70      5    93%
ethstaker_deposit/cli/test_keystore.py                                  23      1    96%
ethstaker_deposit/credentials.py                                       208     78    62%
ethstaker_deposit/deposit.py                                            59     10    83%
ethstaker_deposit/exceptions.py                                          6      0   100%
ethstaker_deposit/key_handling/__init__.py                               0      0   100%
ethstaker_deposit/key_handling/key_derivation/__init__.py                0      0   100%
ethstaker_deposit/key_handling/key_derivation/mnemonic.py               95      5    95%
ethstaker_deposit/key_handling/key_derivation/path.py                   17      1    94%
ethstaker_deposit/key_handling/key_derivation/tree.py                   36      0   100%
ethstaker_deposit/key_handling/keystore.py                              98      0   100%
ethstaker_deposit/settings.py                                           35      0   100%
ethstaker_deposit/utils/__init__.py                                      0      0   100%
ethstaker_deposit/utils/ascii_art.py                                     2      0   100%
ethstaker_deposit/utils/click.py                                        98      3    97%
ethstaker_deposit/utils/config.py                                        3      0   100%
ethstaker_deposit/utils/constants.py                                    29      0   100%
ethstaker_deposit/utils/crypto.py                                       29      1    97%
ethstaker_deposit/utils/deposit.py                                       8      0   100%
ethstaker_deposit/utils/exit_transaction.py                             23      0   100%
ethstaker_deposit/utils/file_handling.py                                13      0   100%
ethstaker_deposit/utils/intl.py                                         55      3    95%
ethstaker_deposit/utils/ssz.py                                          60      7    88%
ethstaker_deposit/utils/terminal.py                                     29     21    28%
ethstaker_deposit/utils/validation.py                                  264     55    79%
----------------------------------------------------------------------------------------
TOTAL                                                                 1698    236    86%

[valefar-on-discord]

🤌 Great stuff