Rework `total_earnings` to `scheduled_rewards`

[bajtos]

We have recently reworked how rewards are paid to Station operators to use the model "push once a month". Station Desktop no longer shows "total earnings" but instead displays "scheduled rewards", see CheckerNetwork/desktop#1082

We need to make similar changes in Station Core and possibly in the underlying modules (Zinnia, Bacalhau) too.

Keywords to search for in the codebase: totalEarnings, total_earnings.

Slack threads started by our users:

• https://filecoinproject.slack.com/archives/C03S6LXSRB8/p1699528485011289
• https://filecoinproject.slack.com/files/U02N6KCL19S/F0652MPRRBN/image.png
• https://filecoinproject.slack.com/archives/C04N76Y689M/p1699512083801239