Improve Git password/passphrase dialog behavior

[fmeum]

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

Improve the behavior of the Git password/passphrase dialog in two ways:

• When the same InteractivePasswordFinder is used for authentication twice, e.g., for the push following a pull in a sync operation, the second prompt should not count as a retry. Otherwise, the remembered passphrase would always be cleared.
• Since we don't want to ask the user for their password/passphrase twice for a single sync operation, the password is now cached for the entire GitOperation and cleared in GitAsyncTasks onPostExecute.

💡 Motivation and Context

Fixes #828.

💚 How did you test it?

I ran a few sync and push operations.

📝 Checklist

• I formatted the code with the IDE's reformat action (Ctrl + Shift + L/Cmd + Shift + L)
• I reviewed submitted code

🔮 Next steps

📸 Screenshots / GIFs