Adding command to create deposit with validator keystore

[valefar-on-discord]

Had bad rebase that broke partial-deposit and had to recreate.

#93

[github-actions]

Test Coverage: Download HTML Report

Name                                                        Stmts   Miss  Cover
-------------------------------------------------------------------------------
ethstaker_deposit/__init__.py                                   0      0   100%
ethstaker_deposit/cli/__init__.py                               0      0   100%
ethstaker_deposit/cli/existing_mnemonic.py                     28      0   100%
ethstaker_deposit/cli/exit_transaction_keystore.py             39      2    95%
ethstaker_deposit/cli/exit_transaction_mnemonic.py             62      8    87%
ethstaker_deposit/cli/generate_bls_to_execution_change.py      63     15    76%
ethstaker_deposit/cli/generate_keys.py                         43      3    93%
ethstaker_deposit/cli/new_mnemonic.py                          26      0   100%
ethstaker_deposit/cli/partial_deposit.py                       61      5    92%
ethstaker_deposit/credentials.py                              197     68    65%
ethstaker_deposit/deposit.py                                   53      9    83%
ethstaker_deposit/exceptions.py                                 2      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      90      7    92%
ethstaker_deposit/key_handling/key_derivation/path.py          18      1    94%
ethstaker_deposit/key_handling/key_derivation/tree.py          37      0   100%
ethstaker_deposit/key_handling/keystore.py                    100      0   100%
ethstaker_deposit/settings.py                                  22      1    95%
ethstaker_deposit/utils/__init__.py                             0      0   100%
ethstaker_deposit/utils/ascii_art.py                            1      0   100%
ethstaker_deposit/utils/click.py                               48      3    94%
ethstaker_deposit/utils/config.py                               3      0   100%
ethstaker_deposit/utils/constants.py                           27      0   100%
ethstaker_deposit/utils/crypto.py                              29      1    97%
ethstaker_deposit/utils/deposit.py                              9      0   100%
ethstaker_deposit/utils/exit_transaction.py                    24      0   100%
ethstaker_deposit/utils/file_handling.py                        8      0   100%
ethstaker_deposit/utils/intl.py                                54      3    94%
ethstaker_deposit/utils/ssz.py                                 50      6    88%
ethstaker_deposit/utils/validation.py                         198     51    74%
-------------------------------------------------------------------------------
TOTAL                                                        1292    183    86%

[yorickdowne]

lgtm

[valefar-on-discord]

#89