Feature: Ask for password and/or ssh-key passphrase on each connection

[mamayer]

I don't want to save the password and/or ssh-key passphrase for security reasons. TablePlus should ask for those if not specified.

Imho there are 3 szenarios for credentials (usernames, passwords, ssh-key, ssh-key-password):

• Empty, because not needed => Can connect without further interaction
• Needed but not saved in TablePlus => TablePlus should ask, when the user tries to connect
• Needed and saved in TablePlus => Can connect without further interaction

Therefore the edit-window would have a checkbox "ask me" for each of the following fields:

• SQL-password (nice2have: +SQL-User)
• SSH-Key password (nice2have: +SSH-User)

If one of the ask-me checkboxes is checked, the user should be shown a promt to enter them when connecting.

Additionally, the ssh-client should use the key from the agent, see #495

Please answer the questions below, it helps us to track the issue.

1. Which driver are you using and version of it (Ex: PostgreSQL 10.0): MySQL, MariaDB

2. Which TablePlus build number are you using (the number on the welcome screen, Ex: build 81): 186

3. The steps to reproduce this issue: Open TablePlus, add or edit a connection, leave password empty and connect. The connection will fail.

4. What is expected: TablePlus will ask for the password, if none is provided, but needed.